Keep losing fish - is this TB?

[Dandy]

Apologies for the long read, it is detailed.

We started fish keeping in December 2018, and around February 2019 we made a terrible decision to purchase some Ramshorn snails off eBay to help with cleaning algae off the tank as we'd read snails are good at that. It worked, but we didn't realise Ramshorn snails are prolific breeders as we hadn't done snail research. The tank soon got overwhelmed with them. Then came our next mistake in April - purchasing Assassin snails off eBay thinking we could control their population. Unknown to us a pond snail had hitched a ride in the package, and we assumed it was just a baby assassin. Nice, a free extra snail! Wrong, this soon reproduced to the point where their numbers were higher than the Ramshorns. At that point I looked at photos of snail species to determine these weren't baby assassin snails but actually pond snails. By June there were literally piles of snails everywhere you look in this 190 litre tank. I'll never forget the horror of seeing about 30 of them feasting on the corpse of a fish inside one of our tank decorations.

Shortly after introducing the Assassin snails our dalmation molly that we had since the start died of what appeared to be a swim bladder infection. He went from healthy to dead in the space of about two days. At this point snail populations were manageable, but still things went from bad to worse. Next, in May our gold/black molly lost the use of his tail and started thinning out until he passed away at the end of the month. We then started seeing guppies developing bent spines seemingly overnight and eventually passing away. Sometimes we'd not even find the remains because the snails would turn them to skeletons overnight. In June we found one of our pink female swordtails floating on the top of the tank and this was even more alarming as the fish had shown no symptoms of anything being wrong. It was healthy and energetic one day and dead the next, possibly stressed from being chased by guppies 1/3 of its size. We knew at this point something was seriously wrong with this tank but couldn't figure out what.

Throughout I had been keeping an eye on water parameters (ammonia and nitrates etc) and nothing was flagging up as bad. Google searches led to horror stories about fish TB as the symptoms (bent spines, bulging eyes etc) were similar. But if so then how could this have gotten into the tank? We assumed it was down to our snail mistakes - they could have been carriers as god knows where they came from. Never buying anything like that from eBay again. At this point we decided we had to get the fish out of there and eliminate the snail population.

We bought a temporary tank (110 litres) a bit smaller than our main tank (190 litres) and put the fish in there - apart from three that looked like they would be next to die. A very skinny dalmatian molly, a guppy with a bent spine and a black phantom tetra that was swimming odd and had somehow lost its sight. These were quarantined in a small tank (15 litres) and they did indeed deteriorate to the point where we felt it best to euthanize them. The temporary tank allowed us to tear down the main tank, throw away the gravel, rid it of snails and start fresh. Even the filter media was binned as it was infested with snails. This tank is still dried out while we buy bits and pieces needed to get it back up and running.

Due to the urge to get the fish out of the infested tank we couldn't fully cycle the temporary tank. Aware of ammonia dangers we've been doing more regular water changes and testing the tank constantly in case of a spike. We've been treating fish for various conditions thinking they had fin rot, parasites or worms. And treated fir white spot which our cardinal tetras seemed to have. We obviously didn't mix treatments, one at a time. But still fish keep dying. Yesterday we noticed a molly sitting upside down on the bottom - it was perfectly healthy the day before. It swam about when food was dropped in before going back to the bottom. I put some swim bladder treatment in thinking it was that but today it was dead. A guppy was also found dead this morning with no explanation or prior symptoms. We also have a black phantom in this tank showing the same symptoms as the last one that died. Seemed to have been like that since it was put in there but wasn't quite as far gone as the other so it never got quarantined. We also have another molly which is very thin and showing symptoms other have passed away from in the past, though no bent spine.

I don't know what's going on, we seem to be losing fish one by one. Only the Cardinal Tetras seem to be doing well as we haven't lost any. Our tank is made up of:

10 Cardinal Tetras
4 Black Phantom Tetras
8 Mollies (5 of which are offspring of other mollies)
5 Guppies (3 are small offspring)
4 Swordtails

I realise this is too many for the 110 litre tank but it was about right for the 190 given the small size of the tetras and the babies that we can't stop being bred. The plan was to get the 190 back up and running this month with new gravel but I am worried these fish are all infected with TB and I don't really want to until fish stop dying.

What do you suggest is the best course of action for these fish?

I am leaning towards keeping them as permanent quarantine in the smaller tank and setting the 190 back up with new fish but that seems a bit drastic as some of these fish are probably fine. However I am worried they are all infected with TB and will infect any new fish we put in with them. We replaced the original mollies with new mollies back in May and the new fish are the first to die - in fact we've lost 4 of the 5 mollies we bought a couple of months ago and the 5th is the thin one I mentioned earlier. Yet we still have two of our original mollies bought in December and 5 of their offspring - all looking healthy apart from the male who fathered them. He seemed to have some fin rot which I've treated but he's still not 100%. Or maybe he has TB, as fin rot is a symptom.

These fish have lifespans of up to 5 years and that's a long time to keep a second tank running in quarantine when we only want one tank. We could also move them all back to the 190 tank and never buy a new fish until they all pass away but that too seems drastic as we obviously would eventually like to replace fish that die with new ones. But we have decided we won't be buying a new fish again until we go a month or two without losing one. We do plan to do a full cycle on the 190 litre tank before moving the fish back there - if they go back there as well.

But I am completely lost as to why fish keep dying and can only put it down to TB. Please help.

 

[FishGuest5123]

Hello! The guppies would be more prone to bringing in TB. A lot of guppies are coming down with it. I doubt the snails have anything to do with it. If you can post a few pics it would help. Also, can you give us your exact water parameters?

 

[Colin_T]

Hi and welcome to the forum

If you have a snail problem, the easiest way to fix it is to add copper or salt to the aquarium. It kills snails and you won't have to strip the tank and dispose of everything. If you wanted to keep the gravel, you can boil or bake it to kill any snails in it. Too little too late I know, but for future reference.

---------------------------
Any chance of a picture and short 20 second video of the fish?
If the pictures are too big for the website, set the camera's resolution to its lowest setting and take some more. The lower resolution will make the images smaller and they should fit on this website. Check the pictures on your pc and find a couple that are clear and show the problem, and post them here. Make sure you turn the camera's resolution back up after you have taken the pics otherwise all your pictures will be small.

If the video is too big for this website, post it on YouTube and copy & paste the link here. We can view it at YouTube. If you are using a mobile phone to take the video, have the phone horizontal so the video takes up the entire screen. If you have the phone vertical, you get video in the middle and black on either side.

---------------------------
Tuberculosis (TB) is a slow growing bacteria that destroys internal organs over a period of time. The most common symptoms include:
Fish swell up over night and die within 24-48 hours of bloating.
Fish gasp at surface or near a filter outlet.
Fish stop eating and do a stringy white poop.

Fish can carry TB in their bodies for months or even years. Bigger fish live longer because it takes longer for the organs to become damaged and eventually rupture, causing organ failure and the fish bloats up due to fluid in their abdomen.

----------
You can't treat fish TB because Mycobacterium cells are covered in a waxy coating, which prevents chemicals harming the bacterium and also protects it from the elements. The bacterium can remain dormant in shady areas or mud for many years. A fish health scientist I contacted about this in 2006, told me he found live but dormant fish TB in a dry river bed down south. The river had not had any water for 7 years, yet they still found live bacteria there. Hot and dry conditions kill the bacteria quicker. It dies in a couple of seconds at 60 degrees Celcius.

----------
People can catch fish TB, however people with a healthy immune system are less likely to develop a fish TB infection. People catch fish TB when open wounds in their skin are infected with TB contaminated water. If you wash your hands and arms with warm soapy water after working in a tank, you are less likely to contract the disease. If you have cuts, scratches, sores or any open wounds on your skin, avoid getting fish tank water on them. Wear a pr of rubber gloves or just stay out of the tank until the wounds have healed.

People with a weakened immune system (heart disease, lung problems, diabetes, cancer, HIV, old people, babies, etc), are more likely to develop localised TB infections.

If you develop any sores on your hands or arms that don't heal up normally or quickly (within 2 weeks), see your doctor and inform them that you keep aquarium fish. The doctor will probably try to put you on anti-biotics, however this is not good. Ask the doctor to take a swab of the sore and send it off for testing to see what is growing in the wound. The lab should culture the swab and test various treatments on it to find out which medication will work best. The results will be sent to the doctor, along with a list of medications that treat the disease. The doctor will then find a medication that is safe and suitable for you.

Do not take anti-biotics for a small sore that hasn't healed until it has been swabbed and identified in a lab. Then take the anti-biotic that works best on that specific bacteria.

People have gone to the doctor with small sores and been put on anti-biotics before a swab was taken. The anti-biotics don't work and the bacterium simply becomes resistant to that sort of anti-biotic. Because the anti-biotics don't work, the doctor prescribes another type of anti-biotic and this continues for months with no improvement. Eventually the doctor will take a swab and send it off for culture, but that can be 6 months later and by then you have big sores on your skin that are gross and can potentially contaminate other people with open wounds.

So just make sure you tell the doctor you keep fish and want any sores swabbed and sent off for culturing before you take anti-biotics.

Before you go to the doctors, or while you're waiting for the results, you can try using raw honey. You wash the wound with warm soapy water, dry it with a tissue, then rub raw honey into the wound. Put a bandage over the wound to stop the honey going everywhere. Remove the bandage and wash the wound and re-apply honey 2 times a day. Raw honey has chemicals in it that kill viruses, fungus, and bacteria and might help with fish TB. You normally see results after 3-4 days of applying honey and you continue using it until the wounds have healed over.

---------------------------
Now that I have scared the hell out of you, I think we should rule out other issues before jumping to TB. Don't buy any more fish until you know what is going on.
Post pics and video of the fish.
Tell me what medications you have used, include their ingredients.

What is the GH (general hardness) and pH of your water supply. This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

 

[Dandy]

Thanks for the replies

For water testing I use the Tetra 6 in 1 strips and a separate ammonia test kit. They don't give exact numbers as they're colour based, but give some idea of the water quality. Everything on the strip is within the green (ok) ranges apart from PH (off the scale belw 6.4) and KH which seems high. The PH has always been at that level on every test I've ever done. I did an ammonia test just now and it is showing between 0.5-1. I know it should be 0, but that reading isn't worryingly high either.

According to the water company's website the water hardiness is Moderately Soft at 24 mg/l as calcium. Not sure what the latter bit means. Can't find information on the PH but I suspect it is low given the tank readings.

I've uploaded a video of the fish to Youtube as requested:

The dalmatian molly is the one that looks thin.
The black molly is the one with a tatty tail. Supposed to be have a lyretail like the orange ones (his offspring) but the ends have broken off. I have treated him for fin rot however.
I can't work out which of the black phantoms is the one with problems, his condition seems to have improved since I added swim bladder treatment to try save a molly a couple of days ago. Though he still has sight issues, which may not be visible in the video.

If you're wondering why the tank looks bare it's due to it being the temporary tank. Plan was to get them back into the 190 litre tank with a new setup as soon as possible, and I don't want to put the decorations in this tank in case they have snail eggs. Although I'm not sure how long snail eggs survive outside water so they may be dead anyway if any exist.

 

[Colin_T]

If your water is soft, then you will always have issues with livebearers (mollies, guppies, platies, swordtails). These fish need a pH above 7.0 and a GH above 200ppm, (250ppm for mollies).

---------------------
Snail eggs die after a day or so without water. If they are dry they are dead. If they are soft and jelly like, they are still alive.

---------------------
The skinny molly has gill flukes and probably intestinal worms. Livebearers always have intestinal worms and gill flukes and you could start by treating that.

You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole.

Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.

You treat the fish once a week for 3-4 weeks. The first treatment will kill any worms in the fish. The second and third treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.

You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too. Wash filter media in a bucket of tank water.

Treat every fish tank in the house at the same time.

Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.

The water changes will remove most of the medication so you don't overdose the fish. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish.

---------------------
You need to get the ammonia and nitrite down to 0. Any ammonia or nitrite in the water will harm the fish and make them more susceptible to other problems. The easiest way to fix this is by doing a 75% water change each day until the levels are 0. Then do a 75% water change any day there is a reading above 0.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

---------------------
You need some substrate on the bottom of the tank to make the fish feel more secure. If they don't have a well defined base, they stress and are more susceptible to problems. You don't need a lot, 1/2 inch is fine. you just need something so the fish can't see their reflection on the bottom.

---------------------
I would set up the other tank (190) and get it running. While it is running I would treat the other tank/s for intestinal worms and gill flukes. Once they have been treated, I would move the livebearers into the bigger tank and add some mineral salts to increase the hardness of the water. And I would leave the tetras in the smaller tank with soft water.

You can use half the filter media from the smaller tank and put it in the filter on the bigger tank when you move the fish across, so you have a cycled filter on both tanks.

 

[Essjay]

The hardness unit mg/l calcium is a favourite of UK water companies

According to the water company's website the water hardiness is Moderately Soft at 24 mg/l as calcium

24 mg/l calcium converts to 60 ppm and 3.3 dH. I would call that soft rather than moderately soft. As you can see from the requirements Colin gives, your water is way too soft for livebearers. While the lack of hardness alone would not kill livebearers very quickly it will weaken them and make them more susceptible to diseases.

Your hardness is perfect for fish from south America and most of Asia.

 

[Dandy]

Thanks for taking a look at them.

I didn't know livebearers hate soft water, we got them thinking they'd be easy to look after. We did have very little problems with loosing fish until about 4 months into the tank though, apart from losing a couple of pregnant guppies. Apparently it's common for guppies to die whilst giving birth from what I read so we thought nothing of that. However might this early success have been due to the gravel being new and possibly releasing minerals into the water to harden it a bit?

I bought a treatment called eSha-ndx last week for treating worms and parasites and put that in, Is that no good for gill flukes and intestinal worms? I'll see if I can find Praziquantel as well.

Any idea what might be causing the black molly's tail to be so tatty? Or is it just fin rot that was treated late? I hear they do grow back but takes time.

What about the fish that were dying with bent spines? That was my biggest concern. Is that something worms could do?

That's a good suggestion regarding the lack of gravel. I have noticed the fish don't like seeing their own reflection on the bottom. We've bought new gravel to put back in the main tank but didn't want to put it in the temporary tank in case these fish are carrying something bad that could end up back in the main tank, but if it's safe then we could use some of that to cover the bottom. I'l stick some in when we do a water change either later tonight or tomorrow.

The filter media can't really be used on the main tank as we have a big external filter for that with large foams whereas on the temporary tank they're just small square pads for the internal filter. I'm happy to let it cycle for a few weeks before putting fish in if need be though.

Also with your suggestion of moving just the livebearers and leaving the tetras in the smaller tank, does this mean it is bad to mix livebearers with tetras? I wonder if this is why the tetras seem to be more successful - they like the softer water. Ideally we don't want to have to maintain two tanks though. Is there no hardiness level that works for both? We can't be the first to mix livebearers with tetras as fish like Neons and Cardinals are quite popular.

 

[Essjay]

The eSHa-ndx that you have used contains levamisole, the medication Colin recommended for round worms (which includes thread worms). eSHa gdex contains praziquantel, the medication for flat worms (tapeworms and flukes)

Mollies tend to suffer most from lack of hard water, and this is why your molly is more susceptible to things like finrot. Unfortunately there is really no 'happy medium'. The only way to keep livebearers in your water is to add chemicals to make it harder. But if you do this your soft water fish will start to suffer. This means two tanks, one with plain tap water for the soft water fish and one with 'hardened water' for the livebearers.



You started this thread by mentioning a snail problem. Snails only take over a tank if there is lots of food for them. In other words, over feeding the fish. Fish need a lot less food than you'd think. Mammals use most of our food to maintain body temperature. Fish get their body temperature from the water, they don't use food for this purpose so their bodies use less food than a similar sized mammal.
Colin does not like snails, he has said so many times. But I am quite happy with snails in my tanks. I have nerites, Malaysian trumpet snails, physid pond snails and those tiny flat mini ramshorn snails. As long as they don't take over a tank they are an important part of the tan's ecosystem.

 

[Dandy]

Thanks essjay. I will buy some eSHa gdex and treat the tank with it. I wish pet shops gave you more information on stocking fish. I mean I bought mollies on the same day as black phantom tetras when we started the tank and no one in the store said mixing livebearers with tetras is bad. I think separating them may be the best way forward, but maybe with a smaller second tank as I don't want to have to maintain a 190l tank plus a 110l. Not really sure what's best as currently we have more livebearers than tetras.

Since my last post I did a 60% water change to reduce the ammonia level and covered the bottom with gravel to avoid the fish reflection problem. However when I started the water change and checked on the health of the fish I noticed none of our original guppies is in a bad state, one with a red/black tail. He seemed fine earlier but has been sitting on the bottom upsidedown. Still alive but doesn't look healthy. The black phantom I mentioned earlier who was ill has also taken a turn for the worse, been swimming around in circles and can't maintain an upright position.

As for snails, I am not against them in moderation. I'd probably get some more now I know more about the different species and get ones which don't breed like crazy. Nerites are a good option for that. I do agree with you on overfeeding. We have been guilty of that and have been cutting down on the food that goes in but maybe not enough. I siphoned loads of uneaten food out from the small gap under the filter when cleaning it. It won't go there now as the layer of gravel will plug the gap.

 

[Byron]

I will not counter any of the advice from other members who have so far posted in this thread concerning disease as they know more (considerably more) about this than I do. My area of expertise is fish species and habitats, so I will reinforce what essjay and Colin said respecting the mollies and swordtails and guppies. And I will go one step further...unless you intend having two distinct tanks, one for livebearers and the other for the soft water fish, so you can prepare harder water for the livebearers, I would strongly suggest euthanizing the livebearers now. They apparently have one or more diseases, so no one will likely want them; but even if you should cure them, the soft water will kill them in time, and given what has occurred here so far it won't be long. Better to put them out of their misery.

Hard water fish in soft water are having a really terrible time just trying to maintain their normal physiological functions. The lack of mineral in the water weakens them more and more, and they are more susceptible to disease and will not live anywhere close to a normal lifespan because of this (the weakening, if not the subsequent diseases). While you can harden the water, it is not all that simple, and it means preparing water for water changes. I and others can detail this more if asked, but keep in mind that this livebearer tank is just for livebearers, and they need space...swordtails and mollies need a 36-inch length tank minimum, and larger depending how many there are/will be. As essjay noted, your soft water fish will begin to have issues if you harden their water. There is no compromise in this situation that is not cruel to some of the fish.

The snails are certainly not an issue, and remember, their numbers will depend solely upon them finding food. They eat all organic matter--fish excrement, uneaten fish food, dead plant matter, dead fish obviously. They are your friends in the aquarium as they do what we can never achieve, getting everywhere to deal with these organics, breaking them down faster for the various bacteria to then handle. Be careful of assasin snails, they are prohibited in some areas because if released (accidentally with flushed/tossed aquarium water for example) into the local ecosystem they can ravage it and cause real harm.

I certainly second the advice not to acquire any more fish, or set up any more tanks, until the issues are confirmed and remedial action taken.

 

[Dandy]

Yeah I've been doing further research on Google on the water hardness thing and lots of people are saying not to keep tetras and livebearers together. We will have to phase out the livebearers and go with a different kind of tank, which is a shame because we like livebearers more than tetras due to how colourful they are. What else can you keep with tetras? We will avoid buying more fish until the problems are resolved, but I can't think of many good alternative fish for colours.

We will have to keep two tanks running I guess, until we don't have any livebearers left. I don't want to euthanise any fish that look healthy. The swordtails are the nicest fish in the tank and seem to be ok so I wouldn't want to just euthanise them. I wanted more of them until discovering the water hardness problem. Gotta say this is all putting us off fish keeping, as the swordtails and mollies are our favourites in the tank.

 

[Byron]

Yeah I've been doing further research on Google on the water hardness thing and lots of people are saying not to keep tetras and livebearers together. We will have to phase out the livebearers and go with a different kind of tank, which is a shame because we like livebearers more than tetras due to how colourful they are. What else can you keep with tetras? We will avoid buying more fish until the problems are resolved, but I can't think of many good alternative fish for colours.

We will have to keep two tanks running I guess, until we don't have any livebearers left. I don't want to euthanise any fish that look healthy. The swordtails are the nicest fish in the tank and seem to be ok so I wouldn't want to just euthanise them. I wanted more of them until discovering the water hardness problem. Gotta say this is all putting us off fish keeping, as the swordtails and mollies are our favourites in the tank.

You other option is getting rid of the soft water fish and devoting the largest tank to livebearers. A calcareous substrate (sand composed of aragonite and crushed coral is one often used) is easiest as it will raise the GH, KH and pH suitable to livebearers but much too high for most soft water species.

Having said that, I do not myself like the livebearers because they are all so much the same except for colour. The world of soft water fish is endless. Almost any fish from South America, SE Asia, and a few from Central Africa are soft water, and that includes all the tetras, rasboras, danios, barbs, catfish, loaches, gourami, dwarf cichlids. Many but not all of them are less active so generally more will work in a tank of a given size.

You do have to do something about the livebearers, they will continue to struggle in soft water and that is not being kind to them, even though you do not mean this.

 

[Colin_T]

It's not too hard to maintain 2 tanks once they are established. If you do set up 2 tanks, you can have your livebearers in the bigger tank and the tetras in the smaller one.

Right now the livebearers look bad because of the water quality (ammonia and nitrite) and because of the soft water. Big daily water changes can be used to dilute the ammonia and nitrite. Using the medication to kill the worms and flukes will help. You can also add some salt, which should help to buy you some time for the livebearers.

-----------------------
You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate will affect some plants. The lower dose rate will not affect plants.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

--------
If you are doing big water changes to dilute ammonia and nitrite, you need to add salt to the new water before it's added to the tank.
eg: you change 20 litres of water, so you add enough salt to the buckets of new water to treat 20 litres.

-----------------------
If you were to set up the second tank and move the livebearers and half the filter media into it, you can add a Rift Lake water conditioner at about 1/3 to 1/2 dose and it will increase the GH, KH and pH for them.
I used a large plastic container and filled it with tap water, added dechlorinator and Rift Lake conditioner and aerated the solution for 24-48 hours before using it. I then used that water on my livebearer tanks.

You can reduce the feeding to a couple of times a week and do a 75% water change and gravel clean the substrate 4-8 hours after feeding. And monitor the water quality for ammonia and nitrite and do a 75% water change any day you have a reading above 0.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Feed and water change the tetra tank the same way.

Continue doing this until the filters have finished cycling, then you can feed the fish more often and do a water change and gravel clean once a week. And then you can start enjoying your fish

-----------------------
Bent spines in fish can be caused by a number of things. Any sort of growth inside the fish (tumor, cyst, bacterial infection, baby fish), poor water quality, old age, low mineral content in the water can cause the equivalent of osteoporosis in hard water fishes.

In my experience, TB doesn't normally cause bent backs/ spines because the organs usually fail due to the infection, well before a large granuloma can form. A granuloma is a large clump of TB infected tissue.

I would set up the second tank, deal with the known diseases and poor water quality. Get the water chemistry correct for the species, and then see how they do.

 

[Dandy]

We've decided that we're going to put the tetras back into the big tank and build around those, and let the livebearers live out the rest of their days in the smaller tank and not buy any more for that tank so eventually (if they stop breeding!) we'll have none left. We'll try improve the hardness of the water for that tank as suggested with something like crushes coral, and treat them for worms and flukes. I'll try adding a bit rock salt as well. We may have to replace the smaller tank though as it was only intended to be a temporary tank and I don't like the giant scratch on the glass. The lights are also failing. (Was a cheap purchase off Facebook marketplace.)

As for the main tank, it sounds like there are a lot of different fish we can get based on your comment Colin but we'll have to do a lot of research. I love gouramis for example but when we added a gold gourami to the current setup months back (before problems started occurring) it was the most aggressive fish I'd ever seen and had to be taken back to the store. It was constantly going for anything smaller than it. Our Cardinal Tetras and Black Phantoms aren't the biggest fish so we may be limited by size as well.

Main reason we didn't want two tanks is because of the effort involved in the water change - carrying heavy buckets to and from the kitchen but we're trying to find a way to do it without that.

I'm glad that it's looking unlikely these problems are TB though. I was worried since it can be passed to people.

Edit: The dalmatian molly we were talking about yesterday with the gill flukes was found dead this morning.

 

[Colin_T]

Use a clear plastic hose or garden hose and a 1, 1.5 or 2 litre plastic drink bottle to drain and gravel clean the tanks. Then you can rinse the hose out and use it to fill up buckets next to the tank. Add a dechlorinator to the buckets of water and aerate for at least 5 minutes, then pour them into the tank.

To make a gravel cleaner out of a plastic drink bottle, you cut the bottom off the bottle and throw that bit away. Remove the lid and plastic and throw them away. The remaining bottle is the gravel cleaner and you can put a garden hose in the top or buy clear plastic hose to fit on the bottle.

-------------------------
Make sure you treat all the fish for worms and gill flukes. If one fish has it, they will all have it.

-------------------------
Gold and blue gouramis (Trichopodus trichopterus) are angry fish and not worth keeping in a peaceful tank.
Dwarf gouramis (Trichogaster lalius) and all their colour forms are riddled with diseases that can't be treated and should also be avoided.