Fish dying slowing one at a time

[chooz]

I am keeping only small fish (<5cm) in a tank with java moss and java fern only. I don't add fertilizer other than trace elements. Even though these small fish are cheap (3-6 fish for S$1), it is not doing good to the inhabitant's and the owner's morale when they keep dying slowing.

My fish (different species) seems to be dying one at a time at the rate of 1 fish per 2-3 weeks. Symptoms are it started to isolate itself, hide, stop feeding and died. Those that are left behind can survive for more than 2 years.

Is this normal for mass produced fish? that they are weaken due to mass breeding?

Or is my fish tank has some stress factors than are causing the fish to die slowing? Those that survive are those that are strong or adapted to the stress?

So it ended up that my tank is currently a "rojak" mix of fish. Luckily, they don't fight each other. But maybe the rojak mix contributes to more stress?

[terence]

Bro, how many fishes do you keep in the tank currently? Are your fishes feeders? Fishes are stressed due to various reason. Could be overcrowding, water condtions, their mates and etc. Share with us more.

[fishking]

Hi chooz...3-6 fishes for $6 seems like very cheap fishes which maybe used for other purposes and not meant for fish keeping.

What fishes are you keeping??

[zhou yuande]

Hi chooz, you may be keeping neon tetras as they normally cost around this price.

[barmby]

Chooz, maybe you want to let the fish settled at the LFS before buying. Nam Hong in Ang Mo Kio is a great place for inexpensive fishes yet they are pretty much stable. But be prepared to pay slightly more (10 -30 cents)

[chooz]

Thanks for all the replies. Answers to the questions as follows:

1. No, I am not keeping feeder fish. In fact, I am tempted to, after reading somewhere that feeder fish (usually platy) is no inferior to those raise for proper aquarium keeping.

2. I am keeping mainly tetra. Have had a few kinds throughout the years ie neon, black widow, red eye, etc. i am not having them all at the same time, but in succession, after the previous batch has almost died off.

3. The tank size is 1.5 feet and I have less than 10 fish at any one time point. So there should not be any overcrowding issue.

4. I know tetras are schooling fish and I buy six of the same kind at one go. The interesting thing is after they slowly die off, the remaining one or two seems to survive forever, even though they are now without their own kind.

I tend to buy them when they are young, hence the low price. Is that the reason why they seem to die easily? If I buy only the big adults, those that are weak would have died off and the remaining that reach adulthood should be strong enough to last for a long time (Unless I happened to buy aging or old adults ). I wonder if the reasoning is correct.

[Philosophos]

So what's your NH4/NO3/pH/KH/GH reading? How do the fish in the store look? What are the symptoms before they die? Do they look different between the store and your aquarium?

-Philosophos

[chooz]

I can't remember off hand what the water parameter values are, but they were all within healthy range of the test kits at that time. They should, since not all fish died at the same time. Just one fish in about 3 weeks gap.

The look of the fish in store and in my aquarium? The ones that live on looks the same in both places. The ones that die will start to behave like I described in the first post above, and they also look smaller than their peers in my tank. Does this imply that they are unhealthy to begin with?

Does any one have this problem with growing up juvenile fish? Mass breeding a culprit? Should I buy only adult fish next time?

[inque]

i think someone sonner or later will ask u for your tank spec.
i'll ask instead lol ........ what is your tank specs?
below i think is the spec/s should provide if other members were
to provide you with a more comprehensive solution/s


Tank size :
Filtration : Internal , OHF , Canister
Media used : Ceramic rings etc etc....
Anti Chlorine and Chloramine brand:
Food:
Feeding habbits: excessive feeding ?
PH:
Fish type/s : i know is mainly tetras

[barmby]

chooz, i think you are culling the weaker ones. this is something that you cannot help. you mentioned one strong evident. the survived one last for a long time. this is a good indication that you are cycling the batch of fishes. sometime you don't know what kind of condition that these fishes live in the farms. sometime the farm water is very dirty (acidic) but arrives at the LFS then your place... water is cleaned (close to neutral pH)

[inque]

chooz, i think you are culling the weaker ones. this is something that you cannot help. you mentioned one strong evident. the survived one last for a long time. this is a good indication that you are cycling the batch of fishes. sometime you don't know what kind of condition that these fishes live in the farms. sometime the farm water is very dirty (acidic) but arrives at the LFS then your place... water is cleaned (close to neutral pH)

with the proper acclimating i think can lower the death rate further abit.

[Czyne]

Those symptoms sound a lot like nitrite/nitrate poisoning. High bioload, heavy feeding and infrequent water changes can all cause this. Adding 6 fish at around 2 inches each all at the same time may also be part of the initial problem.
Some fish are more sensitive to this than others, and over prolonged periods of time it can weaken their immune system to secondary infections as well.
Along with the questions inque provided, I'd also like to know:

What test kits you are using, and if they've expired:
Are you dechlorinating the water before adding it to the tank:
How often do you clean or change your filter media:
How do you clean or change it (ie: replacing it all at once or using declorinated water for cleaning):
How often do you perform water changes, and how much water do you change:
How many fish are in the tank, and what species are they:

Sorry if some of these seem too obvious, but it often saves a massive headache to rule them out first.

[chooz]

Here is a link to a simple academic paper on nitrite poisoning study in danio:
http://vfu-www.vfu.cz/acta-vet/archi...0877030455.pdf

[barmby]

Influence of nitrite on fish growth, growth suppression in higher nitrite concentrations. Good for people who wants to raise frys. Good to know.

[Czyne]

That was an interesting paper, thanks for sharing! Wasn't expecting as high as 53&#37; stunting in higher levels of nitrite; and in danio rerio at that.
I'll have to read it over again later to see if they state where the lethal dose sits in comparison to the sub-lethal amount used on those test groups, or look for a source with more info on that. Will add it to my bookmark collection either way, it's a great reference.