Help! My fish are dying!

[suev]

I have three tanks - the largest is 5' and the other two are 2.5'. The largest is fine - I have no problems with it at all but one of the smaller tanks was crystal clear one minute and completely thick with something or other a few hours later. I did a 75% water change and removed the live fish into another tank which had been set up for a week (lucky!) some of the fish are still in there including a bristlenose, chain loach, numerous corydoras and two loaches. They seem not too bad except the chain loach who keeps swimming to the surface. I looked this morning and the tank is starting to have the same problem. The plants are thick with what looks like food debris and so is the gravel. The fish I moved were white 4 month old sailfin mollys, the mother, neon and cardinal tetras, and a few others! The only survivors are the mollys and two tetras. The tank they are in has good water, filtration, airation and temperature but there is still something wrong with the fish 4 days after the problem started. They are all at the bottom of the tank most of the time. I have limited there feeding etc but yesterday I lost yet another fish! The only two things I can possibly put it down to are that a couple of weeks ago we lost power whilst I was at work although why didn't this affect the larger tank and that I gave them frozen krill instead of their usual bloodworms but then again why didn't it affect the larger tank?? I'm completely lost and don't know what to do- please someone help - I have lost 14 fish so far and don't want to lose anymore!!

 

[HandsomeDevil]

Sounds like an ammonia spike, Were you cleaning the tanks the day before it happened? Have you tested your water? I suggest another 50% water change and perhaps test for ammonia, chlorine etc,
Hope this helps and good luck.

 

[suev]

Thanks - the water change I did was 3 days before it happened and everything seemed fine - water chemistry the lot! All the fishes were smiling and happy! Do you think that the krill may have been contaminated in some way? I have taken your advice and done a 50% water change in the original 'bad' tank but I'm a bit wary of doing the same in the tank where the mollys and everyone now are incase I stress them out! It's a bit weird that they are still swimming at the bottom cos usually they're middle to top - and they keep hiding under the filter! It's starting to freak me out as I got the new tank because my big tank is a tad overloaded with fish I've aquired! I'm frightened of moving anything - I'm not too good at this death thing!

 

[FSM]

Do you use a water conditioner?

 

[ziggy2]

Sounds like you are having a mini cycle or your tank crashed. I would imagine you have some decaying krill still in the tank. I would do more water changes. It can't hurt.

 

[suev]

Yep - used water conditioner - I used Tetra Aqua Easy Balance and Ammo Lock! You are right about the Krill - when I did the 75% change there was loads of it still floating about when I got it up and running again despite vacuming the gravel etc. Thing is it looked like there was a whole lot more in there than I actually put in - that tank obviously didn't like it!! The Mollys and 2 tetra still seem to be around the filter and at the bottom of the newly set-up tank - is there any specific reason for this?? The pet shop bloke said it's cos they're getting used to it (he didn't even know what krill was!) so I'm not so sure although they do all look ok and swimming about etc., just at the bottom!This tank has been treated with the above too and is crystal clear - should I do a water change in that one or just leave it for a bit? Thing is - I need to get some of the fish from my largest tank in there but obviously don't want anymore mishaps!