Urgent Help Needed With My Tropical Tank :(

[Stebbz]

Hi there. I have been having issues with my tropical tank for around three months now. Nothing I seem to do is stopping my fish from dying. Any advice and suggestions would be greatly appreciated.
Thanks

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Tank size: 100litre
pH: 6.0 ***
ammonia: unsure
nitrite: 0
nitrate: 40
kH: 40
gH: 120
tank temp: 36'C

Fish Symptoms (include full description including lesion, color, location, fish behaviour.
Fish have been dying one at a time. They seem to change body shape first, seem thin but also a bit deformed. It takes around 3-7 days then they die!

Volume and Frequency of water changes:
I normally do 50% every month. I did do 80% the other week as I was moving house but the problems with the fish have been well before this. I have lost two fish since the move, one showing symptoms before then also.

Chemical Additives or Media in your tank:
I add aquarium salts as I read it can keep fish healthier. I have to say I don't use as much as to make it a salt water tank, I just sprinkle some in every few water changes.

Tank inhabitants:
I have a small shrimp and a snail. Other than that it is purely mollies, all born in the tank. I have approx 13 some fully grown, some 4 weeks old.

Recent additions to your tank (living or decoration):
Some new living plants, problems started well before this addition.

Exposure to chemicals:
I don't use house sprays that would get into the tank. Occasionally I see cat hair floating on the top.

Digital photo (include if possible):

 

[Munroco]

A pH of 6 is not good for mollies I'm afraid. They prefer much higher PH. Is the PH in your new place the same as the old? You would do well to find out the ammonia levels as they are probably the most important.

 

[eaglesaquarium]

That pH is likely the biggest trouble for the fish. Mollies are high pH and hard water fish. In low pH and soft water, they die fairly quickly. Their bodies just can't handle it.

 

[NickAu]

What sort of filter do you have?
Is your tank cycled?
 

tank temp: 36'C

I hope this is a typo and you mean 26.
 

I normally do 50% every month.

How many Mollies do you have?
I think you need to change water more often.
 

I add aquarium salts as I read it can keep fish healthier. I have to say I don't use as much as to make it a salt water tank,

How much salt do you add? Eg grammes/teaspoons/tablespoons per gallon?
 

, I just sprinkle some in every few water changes.

You should never do this, What you do is pre dissolve the salt in a liter of tank water, then slowly pour the water in.
 
When you change water how do you de chlorinate it?
 

nitrate: 40

This should be kept as low as possible

 

[Stebbz]

Thanks so much for all your comments.
Re the salt I had no idea, I was given some by a friend so had no pack to check instructions. He did tell me to use 4 teaspoons for my size tank. I only used about half that as I was worried about evaporation making it too salty!
I have no idea what the ph In my tap water is but I've only moved around the corner and this time last year my mollies were all healthy and breeding like crazy. All the young survive which made it very cramped so I rehomed some to family and friends. My ph was up a few weeks ago and I was told (by pets at home adviser) to add a chunk of cutle fish into the tank (I do this now and again if my snail looks like he needs some for his shell) I don't think this made any difference. Any advice how I can get more alkaline? I will go get an amonnia test kit. I thought the sticks I had did everything but obviously not.

I have no idea what type of filter I have, it came with the marina tank. I put three cartridges in (co2 ones) change one of them every 3 weeks.
A guy in a pet shop suggested I should rinse them in old tank water rather than under the tap which I now do.

I use aqua safe added to tepid tap water for water changes.

As for 'is my tank cycled' I only learnt about this yesterday when I found this forum. I had my tank established for 2 weeks before fish went in and I only lost two fish in the first 3 months so I thought that was ok (literally died the day after I got them)
I think I may feed them too much, I had loads of fish at one point and I think me and my partner still give them the same amount of food now!
To help my tank cycle, would it be right to stop feeding then so much and miss a day or so, do a gravel Hoover and partial water change? I feel like I want to change a couple of the filters but after reading about cycling I'm worried my instinct to clean may make it worse!

When everything was good in the tank I had a small plec. I wonder if he was helping the dynamics of the tank.

I still don't get why the fish go all deformed before they die. I was convinced it was parasitic.

Nick, what water change do you recommend? And how often.
Thanks
Also goodness yes the 36'C was a typo it's always around 26!
Nick I have around 13 mollies (very hard to count!), all born in the tank from 4 originals I got when I first got the tank.

 

[eaglesaquarium]

Minimum of 25% weekly, but more is better.

 

[Munroco]

Shells are meant to be good for upping the hardness of water as they dissolve slowly. I've never used this method though, only read about it so I wouldn't know how many.

 

[NickAu]

He did tell me to use 4 teaspoons for my size tank. I only used about half that as I was worried about evaporation making it too salty!

You are using 4 teaspoons in 100 liters. If water evaporates from the tank you just top it up with unsalted water. 
 
When changing water, If you change 25 liters of water you add 1 teaspoon of salt to the new water.
 

I use aqua safe added to tepid tap water for water changes.

Bad idea unless you make sure that the water you are adding is the same temp as the water in the tank.
 
 

do a gravel Hoover

As I do not vacuum my gravel I have no advice on this, Maybe somebody else will have input.
 

partial water change?

Yes, You need to bring the Nitrate levels down. and keep them down, The best way to do this is with water changes as needed. this may mean every few days.
 

Nick, what water change do you recommend? And how often.

I do a minimum 50% every week,  Sometimes I do it more often especially  on my Betta tanks. Never be afraid to change water.

 

[NickAu]

Sorry mods I had to do it this way as I exceeded the number of allowed quotes.
 

(I do this now and again if my snail looks like he needs some for his shell)

With a PH of 6 that cuttle bone should be in the water all the time, If its not your snail will suffer shell erosion.
 

Shells are meant to be good for upping the hardness of water as they dissolve slowly.

So is cuttle bone and crushed coral.
 

I still don't get why the fish go all deformed before they die. I was convinced it was parasitic.

I have no idea why.
 
 I had a Molly that wasted away like that once, luckily none of my other mollies got it.

 

[BeckyCats]

My comments here are based on experience with a tank at work and a molly I brought home.
 
Mollies must have harder water or they will get the shimmies and eventually die. If your water is soft, rehoming the mollies and getting soft-water fish is an option to consider.
 
I would definitely do a gravel vac once a week. This will remove any dead molly babies that fell into the gravel and rotted (I know, gross, but it can happen). If you have little corpses down there rotting, the ammonia levels in your tank will not be good. This happened in the tank at work because no one was vaccuming the gravel and between the fish rotting and the fish poop, the gravel was revoltingly gag-o-riffic. If your tank is heavily planted, you can get away without the vacuuming, but if you only have a few plants, or none, then you will have to vacuum. Vacuuming also removes water, which is a great way to do a water change. Don't do the whole surface of the gravel at once because a lot of beneficial bacteria resides there and you don't want to get rid of it. At least, this is what I have read. It seems possible to me that the bacteria might not be that easily vacuumed up, but I am not an expert on this. If you do a third of the gravel at a time, once a week, this should be safe just in case. My only concern is if you haven't vacuumed before and you don't have enough plants to absorb the nutrients, that the gravel may be more harmful not being vacuumed, than it would be by losing a bit of beneficial bacteria.
 
At any rate, look up fish tuberculosis. It causes wasting and deformities like you describe.

 

[Stebbz]

Nick, 50%? Gosh that's so much. I've always been scared I change too much. My brother who kept tropical fish for years I think was lucky, he hardly ever changed the water, had no live plants but rarely lost any fish! He keeps telling me I do too much! I'm really grateful for your helpful advice. Yes the cutle fish I put in now and again and leave it in there to slowly dissolve. I think I must need more in there maybe.

My comments here are based on experience with a tank at work and a molly I brought home.
 
Mollies must have harder water or they will get the shimmies and eventually die. If your water is soft, rehoming the mollies and getting soft-water fish is an option to consider.
I am going to get a test kit for my tap water to find out. I couldn't rehomed these fish in case they have something contagious. I'd feel awful if they wiped out my friends fish too!
 
I would definitely do a gravel vac once a week. This will remove any dead molly babies that fell into the gravel and rotted (I know, gross, but it can happen). If you have little corpses down there rotting, the ammonia levels in your tank will not be good. This happened in the tank at work because no one was vaccuming the gravel and between the fish rotting and the fish poop, the gravel was revoltingly gag-o-riffic. If your tank is heavily planted, you can get away without the vacuuming, but if you only have a few plants, or none, then you will have to vacuum. Vacuuming also removes water, which is a great way to do a water change. Don't do the whole surface of the gravel at once because a lot of beneficial bacteria resides there and you don't want to get rid of it. At least, this is what I have read. It seems possible to me that the bacteria might not be that easily vacuumed up, but I am not an expert on this. If you do a third of the gravel at a time, once a week, this should be safe just in case. My only concern is if you haven't vacuumed before and you don't have enough plants to absorb the nutrients, that the gravel may be more harmful not being vacuumed, than it would be by losing a bit of beneficial bacteria.
I do have plants but not loads, I will get some more I think, in the back of the tank where the vacuum struggles to reach maybe.
 
At any rate, look up fish tuberculosis. It causes wasting and deformities like you describe.

One image on google kind of looked like mine but mine has no skin changes or wounds etc. They just got all sucked in around abdomen and get an arched back! I'm hoping the problem with them is the ph. I can try fix that fairly easily.

Many thanks for your help
I'm so obviously new at this posting quotes!!

 

[Byron]

Before jumping to the conclusion this might be TB or something, it is much more likely to be due to the soft and acidic water as several have mentioned.  Mollies absolutely must have moderately hard or harder water, and with this the pH will be basic (= above 7, a pH below 7 is acidic).  It is the GH primarily that is crucial.  Mollies kept in soft and acidic water do not last long.  They develop various issues that externally may be shimmying, deformations, fungus--any or all of these.  Salt is OK with mollies (though not necessary, that's another story) but it is not going to replace the other essential minerals such as calcium and magnesium which are lacking or insufficient in soft water.
 
I can suggest ways around this, if you can let me know the GH and KH of your source water (tap water alone).  I will assume it is going to be close to the numbers given in post #1, but the GH and KH can be affected by other factors in the tank so let's have the source water parameters.  And the pH while you're at it.  I again assume you have a test, is it strips or liquid, and which one?  For our purposes here, you could easily get the GH, KH and pH from the water data on the municipal water authority's website, or call them; I would suggest this regardless, as we will then be certain of the exact numbers.
 
Alternatively, as you seem to have soft acidic water, you could decide to go with fish that will thrive in this, as Becky mentioned.  Almost any fish from SA (all the tetras, pencilfish, hatchetfish, catfish) and SE Asia (rasbora, danio, barbs, gourami) are soft water species.
 
On the water changes, I do 50-60% of my tanks every week, sometimes more.  You cannot overdo water changes, though once a week with a decent amount should be sufficient.  Vacuuming into the substrate is good, though if you have live plants the substrate can usually be left alone.  The volume can somewhat depend upon the tank size and fish load, and it is certainly true that some aquarists rarely if ever do them...but without getting into a detailed scientific explanation I can assure you the fish will always be healthier with water changes.
 
You have too many mollies in a 100 litre tank.  Are they really fully grown?  This fish attains three inches for males, with females close to five inches and some even six.  They need space, even as they grow, but the water parameters are against them here so we can deal with this later as part of the solution.
 
Byron.