Fish Dying One By One

Polaris

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Hello all,

This is my first visit to this forum and sadly it comes as a result of problems with my tank. The problem is that all of my fish are dying one by one, and I have no idea why. The fish seem perfectly healthy one minute, with no sign of illness or disease, and the next minute they are dead or dying on the bottom of the tank. Every morning I dread going into the fish room because there have almost certainly been some deaths overnight, and I feel very helpless and disheartened.

The tank is a Fluval Vicenza 180 bow-fronted with external filter which has been running for about 10 months. I have performed regular water tests and the chemical levels all seem normal (I have listed them below). The tank is currently populated by Swordtails, Mollies, two Golden Loaches and a single smaller loach whose name I forget (about 1.5 inches long and brown in colour). In addition, there are several Swordtail and Molly fry in there which were all born between one and three months ago. The deaths have been almost exclusively the Mollies, starting with the first-born young fry (which had grown to almost 2 inches in length), followed by the adult Molly fish. A healthy male Swordtail also died under the same circumstances recently too. Previously I had several Guppies in the tank, all of which died as well within 2 months of purchase. The only Guppies I now have are two in the separate quarantine tank, which seem very happy indeed (I am afraid to transfer them into the main tank!) and one surviving baby Guppy which is in a small fry tank in the main tank.

One further problem, which I am uncertain as to whether it is related to the fish deaths or not is that the water has become very cloudy and murky (despite the chemical levels showing as completely normal). This seemed to have started when we did a water change in order to set up a separate 'hospital/quarantine' tank about 2 months ago. Almost immediately after that, the water in the main tank turned very cloudy, to the point where the fish could not be seen. The water change was only about 10% at any one time, but we did two such water changes in the same week and I fear that we may have triggered a mini-cycle by doing this. It is a green coloured cloud and I wonder whether this could be either an algae bloom or whether we may have triggered a mini cycle by changing so much water at a time (but as I say, the chemical levels are certainly at normal levels now). The cloudy water does seem to clear over time, but never completely, and any little intervention in the tank (such as vacuuming the gravel, or cleaning the filter) seems to make it cloud over again. Because of this, I am afraid of performing water changes or cleaning of the tank ornaments for fear of making the cloud worse, or upsetting the chemical water balance. I am attaching a photograph of the current state of the tank.

The tank information is as follows:

Tank size: 180 litres
pH: 7.6 - 7.8 (has been like this for the last month)
ammonia: 0
nitrite: 0
nitrate: 0 - 5
kH: 6
gH: 16
tank temp: 24 degrees

Fish Symptoms (include full description including lesion, color, location, fish behavior):

No obvious physical problems with the fish. They appear to swim around normally and there are no visual problems with them until the final two or three days of their lives when they slow down slightly, and then just die.

Volume and Frequency of water changes:

10 litres once per week prior to the onset of these problems. However, I have temporarily halted water changes as these seem to make things worse.

Chemical Additives or Media in your tank:

Have used products such as pH Up and pH Down to control pH levels in the past, but the last addition was at least a month ago, and pH levels are now stable. I am trying to avoid adding chemicals to the tank, but did use a dose of Stress Coat yesterday to try to save an ailing Molly (it died anyway).

Tank inhabitants:

1 adult red female Swordtail
2 Golden Loaches
1 Unknown small loach
1 remaining Molly (there had been 4 adult Mollies)
4 young red Swordtails (born about 4 months ago and growing healthily - now about 1.5" to 2" in length)
2 young Mollies (born about 2 months ago - 1 inch long and so far surviving when all their siblings have died)

In separate little fry tanks within the main tank:

1 baby Guppy
4 baby Swordtails (3 of which were born a week ago)
25 (Approx) baby Mollies (whose mother has since died). Over 50 of these were born at once, and I am losing them at a rate of about 2 or 3 per day.


Recent additions to your tank (living or decoration):

None (except for new born fry)

Exposure to chemicals:

None known

Digital photo (include if possible):

Attached.

If anyone can help me to prevent my fish from dying I would be most grateful. Thank you for your time in considering this post.
 

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Just trying to give you ideas. Could it be that with the algae/green water you may be having an oxygen problem? You could try an air stone or bubble wand and see if that helps.

You have a green water problem. This is not supposed to be dangerous to fish. Keep up with your water changes to keep water as clean as possible for the fish. Some people cover their tank completely and leave the lights off for 3-4 days and then do a huge, 80% water change. I did that and got a UV sterilizer and that solved my my green water problem.
 
personally I'd do 20% change every week untill the tank has matured then drop down to 10% bi-weekly

to clear your green water issue try sera aquariaclear or interpet green away.

as for your fish dying it is most likely due to the pH swings that happen when you use the chemicals.
stop using them, never use them again and all should be well.
HTH
 
Do you use a water conditioner when you replace any water in the tank?
 
Might be a silly question but I have no idea how "experienced" you are?

How are you cleaning your filter pads/sponges etc? Not in tap water? but with old tank water?

I wouldn't worry about how much water you're changing, I do at least 40 litres a week on my 125l and have done for over a year with no problems :good: I've also done pretty much a 100% water change on 3 occasions where I've had to move the tank. Water changes are the best thing you can do providing it's temperature matched and dechlorinated. :nod:
 
If that is green water algae you could always put a bunch of live daphnia in there which will eat the algae. I highly suspect that is an algae outbreak, though I would seriously consider doing a massive water change to reduce it significantly. Hopefully OldMan47 will comment here.

Edit: Looking at the picture, it may have something to do with the amount of natural light that tank is getting.
 
Thanks for all the responses.

To answer the various questions:

  • I should have mentioned that I do already have an air-stone in the tank, though I don't use it all the time because it's noisy and creates a lot of turbulence in the tank because of its power; I think it might tire out the young fish with all the effort they have to put in to swim in the currents it creates! However, hopefully it will be providing enough oxygen for the tank when I use it.
  • I've stopped using the pH chemicals now
  • I have tried Green Away and Accu-Clear to clear the green algae, but they don't seem to be working.
  • I do condition the new water with 'Tap Water Conditioner' to remove the chlorine from it before adding it to the tank.
  • I do use old tank water to clean the filter pads / sponges, not tap water.
This morning I have three more dead baby Mollies. Last night I did a 10% water change and unfortunately this morning the green algae cloud (if that's what it is) is worse than ever. As I said in my original post, it seems to go much worse after any kind of intervention I make in the tank. I'm sure if I do a very large water change that would clear a lot of the algae, but I'm scared of killing even more fish by doing such a large water change, and this leads me on to my next question which I hope someone might be able to help me with:

If I do a large water change, won't that remove much of the beneficial bacteria which needs to exist in the tank? Won't I trigger a cycle by doing so? I actually thought that I had caused all of these problems in the first place by performing too big a water change. Can someone please clarify this for me? If it is perfectly safe to perform a large water change then I will do so in an effort to clear the water.

Thanks in anticipation of any further help!
 
I have tried Green Away and Accu-Clear to clear the green algae, but they don't seem to be working.
IME Sera is the only one that works every time, it is pricy but well worth it.

If I do a large water change, won't that remove much of the beneficial bacteria which needs to exist in the tank?
no, the benificial bacteria is in the filter and to some degree in the substrate, what is free floating in the water is negligable.

Won't I trigger a cycle by doing so?
nope.
 
Hi, from the pic it appears your tank is receiving alot of light, the room it's in is very bright and with the tank light on will further feed the algae, reducing the lighting by turning the tank light off and shading the room may help somewhat, I agree a water change will not help matters and may make things worse, if you are finding fish dead in the morning it's because at night with no light the algae is using up oxygen so it is best to leave the bubble wand that you have on 24/7 at the moment whilst you have this algal bloom at least, don't worry about the fry struggling they can get out the flow if they want to, rising the filter outlet above the water level so it splashes on the surface of the water will also help to circulate oxygen if it has a venturi valve this can be used instead of the bubble wand, another thing looking at the decor of the tank there appears to be very little in the way of live plants, planting the tank up will reduce the amount of nutrients available to the algae as the plants will compete directly with them, it appears your tap water has a lot of nutrients, what area do you live in? I've never had a tank get an algae bloom before so I've never had to treat one but I hope I have helped a little :good:
 
Thanks for the further replies. Yes, the room is quite bright, especially during the summer months; I have the tank in my conservatory. :unsure: I've tried to remedy this (temporarily at least) by leaving the light off and partially covering the tank with a towel for the moment. I have also done a large water change (about 50%) and this has certainly helped to reduce the green algae bloom. Hopefully the filter will be able to handle the rest of it, though if not I will do another water change at weekend. If that doesn't work I'll try some of that Sera Aquariaclear. It does seem to be getting better anyway.

Unfortunately the young fish still seem to be dying though. Only the Mollies; the Swordtails seem to be doing fine. Maybe they are a hardier breed, though I thought Mollies were quite hardy fish too.

I have taken the advice to leave the air stone running all the time, and will try to get some live plants in there as well. I did start off with live plants many months ago but they seemed to rot and get a stringy algae-type substance growing on them so I replaced them with plastic ones which are easier to clean and maintain. However, if the live plants serve a purpose then I will certainly reintroduce them.

[I live in Bolton, North West England. We're supposed to have really good water quality here. Well, good for humans, but maybe not for fish!!]

Thanks again for the help.
 
Hello folks,

I am pleased to report that I seem to have solved all the problems with my tank, so I thought I would report back here to thank you all for the help, and also to say what remedial action I took in case it might help someone else with the same problem(s).

First of all, the green algae cloud. I don't believe this was the cause of my fish deaths (just coincidental), but it was troublesome nonetheless and I couldn't even see my fish! As a result of the advice I received here I did a very large water change (about 60%). Naturally this cleared the water to a large extent straight away. The filter then took over and within a day or two the whole tank was crystal clear again. The fish suffered no ill effects as a result of changing so much water (which I was initially very apprehensive about).

Closer observation of the dying fish led me to a proper diagnosis of the problem: Livebearer Disease (or Molly Disease) (http://www.gbasonlin...sease_chart.htm). Prior to their deaths, my fish would stay in one place and 'shimmy'. As the name would suggest, Mollies seem to be more susceptible to the disease than other fish, and this was borne out by my own experience: the Mollies were the main casualties (I lost them all) but it was affecting my other fish as well. Having diagnosed the problem, my research suggested that there might be a shortage of electrolytes in the water which the fish require. I re-examined my water conditions, and it turned out that my gH and kH levels were not what I originally thought they were. When I originally started this thread, I had used one of those multi-test strips which you dip in the water. This supposedly included kH and gH in the test. However, I decided not to trust this potentially unreliable test and bought separate JBL test kits for gH and kH (gH, kH) which showed some very different results. My kH was down at about 3 and my gH was about 6. With this in mind I bought some JBL AquaDur Plus salts to raise both the kH and gH levels. I added it very gradually, and the kH and gH levels gradually crept up (kH is now 6 and gH is now 11). Since that time I have had no further fish loss (other than some fry which were already ailing anyway) and my fish have been much more active and healthier-looking for the past few weeks now.

I'm really pleased with the results and I am confident that I have found the cause of my problem. I am intending to buy some more Mollies now, hopeful that the water conditions are much more conducive to their survival. Once again, I would like to thank the people on this forum for their help, and I hope this post might help someone else with this problem too.
 
Wow -- congratulations, and kudos for your research and persistence. It's a good story of how sometimes more hidden water conditions can affect the health of a tank. Thanks for sharing your story. I'll definitely keep it in mind when I'm trying to get to the bottom of a new problem. :good:
 

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