Fish dieing

[MikeL]

I've have a tank that is almost 4yrs old. Within the last 6 months I've been slowly loosing my fish. Before that I lost a rainbow fish a year and a half before the others started dieing off.

The tank is a 10 gallon that started off with 3 danios, 1 swordtail, 1 oto, and 1 cory. All have been in the tank since it was cycled. First one danio went than the oto a month or so later. I added two danios in and everything was fine. Than another of the original danio died and two months later my swordtail died. The second danio that died always had a big belly but it looked especially swollen before he died. The swordtail looked a little weak for a 10-14 days before he died but not bad.

Ammonia and nitrites are steady at 0. Nitrates are a high at 40 ppm but steady since the tank cycled. Even water changes doesn't affect it much. No plants currently in the tank.

Any ideas as to what may be causeing this slow die off? Old age maybe?

 

[shaunakadub]

I think the life expectancy of Danios in a healthy tank is roughly 5+/- years, so it could be old age.

As for oto's, I've heard they are sensitive, but again you said it had been in there for 4 years and none of your water levels are bad, so again.. possibly old age.

 

[Fishyfanatic]

It could be old age. Are any of the fish acting abnormal now? Were they acting normal prior to the deaths?

 

[greenmaji]

Welcome to AA!
Stagnant high NO3 conditions can and will shorten the lifespan of fish.
It usually shows up with hard water as well.

If you would like to try to get things back in order, I would suggest increasing the frequency and or percentage of your water changes.

It may seem that I'm assuming a little but from the 40ppm NO3 reading it suggests infrequent or insuffecent water changes.

 

[7Enigma]

That or food/waste rotting on the bottom of the tank causing a greater bioload that for the amount of fish in the tank.

MikeL, do you use a gravel vac to pick up uneaten food and fish waste? I see you have a cory which will do a good job of cleaning up the uneaten fish food, but its still possible that fish waste or food is rotting on the bottom (maybe out of reach of the cory). What is the nitrAte level of your tap water? 40ppm if true is very high and approaching the level of unsafe to drink (for my state, I believe it is the cutoff limit for unsanitary water).

If your tap water is at 40ppm nitrAte, I'd find out as much as you can about your water supply (is it well water, are you located near a farm or industrial area, is it public water that will have water sample data).

Congrats on having a tank so well established. It very well might just be natural old age just hitting several fish at the same time, which while it seems like they may be related, are just random events close together.

 

[MikeL]

The tap water is around 20 ppm. I usually change the water, 2-3 gallons in a 10 gallon tank, every week or so with a gravel filter. I change and clean the filter once a month.

Only the swordtail was acting weak before he died. His rear half drooped down more than usual for a couple of weeks. He swam around fine until two days before he died. At that time he just stayed in one place. He also looked skinnier.
One danio always had a swollen belly but it had gotten bigger before he died.
The other danio was fine.
I'm not sure on the Otto since he always just sat around.
Currently all the fish look fine. The Cory hides in his cave mostly and 3 danios swim all over the place. I added a snail to help control the algea.

If I switched to useing bottle water what kind should I use, spring, drinking, distilled, ect. ?

Also, some of the plastic "wrap" around my heater is coming off. Could the fish have eaten some of this and it clogged their intestines. Should I get a new heater?

Last question. Any suggestions on the new fish I should add. I'm thinking of just going with three tetras and have a busy looking tank. However, I kept getting ich whenever I had tetras in there initially.
I always felt sorry for my swordtail since he didn't have any friends.

 

[jcarlilesiu]

I would suggest getting a new heater if its wearing out, they arn't very expensive. Other than that it seems as though your maintance and readings are pretty accurate. I had a ten gallon previously, and i had a hard time keeping my NO3 down with no ill effects. I would consider old age.

My mollies both will sit with their tail fin lower than their head, usually i think they are sleeping.

 

[greenmaji]

even with your tap water NO3 levels water changes could get your ppm down in the 25 range.

And no I don't think the heathy life expectancy of most fish is less then 5 years.

 

[Fishyfanatic]

Do you know the approximate age of each fish prior to the purchase? They could very well be older than 5 years. When fish die it can sometimes be very difficult to determine the cause unless there is an obvious physical change.

I do suggest purchasing a new heater, preferably one that did not have the wrap on it. Our older glass VisiTherms have black lettering that keeps coming off. The Visi-Therm Stealth is an excellent product that does not have the wrap.