Worried about my 15gal tank. Whats wrong?

Lately a lot of the fish in my 15gal tank have died. I started with 6 zebra danios, 2 leopard danios and 6 neon tetras. I now only have 1 zebra danio, 1 leopard danio and 3 neon tetras. I don't know what's wrong. I do weekly water changes and I test the water weekly as well. The water always seems fine. Sometimes the NitrAtes are higher than 20 but then I do an extra water change if that happenes. I tested the tank on friday Ammonia = 0 NitrAtes = 10 NitrItes = 0 PH = 6.8.

The fish don't appear to be ill before they die (except one on the zebra danios had dropsy but died before I treated him), so I never know if they will die or if they are ill. I think one or 2 of the danios died from old age as well, but some have no symptoms at all. I don't know how to help them. :-\

what could be wrong?

Gwenz ???

 

Mmmm. That's no good.

Could it be that there is aggression and you don't see it (e.g. it happens at night)? If it tends to be same-sized fish that die, perhaps a possibility
Have you put meds in it a while ago and not cleared it with activated carbon?
Have you put decoration or other object that may not be aquarium-safe, thus poisoning the water?
Are there many fluctuations in your water's pH or temperature?

 

how much aeration does your 15 gallon have? is there anything at all different about the way they swim, breathe, eat, anything that you can think of? when they die, they still have full color?

 

Mmmm. That's no good.

Could it be that there is aggression and you don't see it (e.g. it happens at night)? If it tends to be same-sized fish that die, perhaps a possibility
Have you put meds in it a while ago and not cleared it with activated carbon?
Have you put decoration or other object that may not be aquarium-safe, thus poisoning the water?
Are there many fluctuations in your water's pH or temperature?

- Maybe there's aggresion at night, because sometimes I hear a few splashes. :-\ But I only have danios and neons and its the danios that seem to die. The neons are smaller than them. Could the neons be aggressive towards them as there is only 3 of them?
- I have used meds but have always put activated carbon in afterwards.
- I've used the same decorations since I set the tank up back in April 2006.
- PH has always been 6.8, temperature is 26 'C (but its been very warm lately so water temp rises higher sometimes)

how much aeration does your 15 gallon have? is there anything at all different about the way they swim, breathe, eat, anything that you can think of? when they die, they still have full color?

- There is an Air stone in there, and I use Tetra-tec air pump to power it.
- Not really anything to tell me that they are ill. The ones I think that died of old age didnt swim much and rested a lot but did swim around and eat well. The others I can't think of anything except one of the neons swam on his side sometimes, but not always. One minute he'd be fine next he'd be swimming on his side. :-\
- They all had full colour before they died, yes.

I'm really confused as to what's wrong and how can I help the 5 fish I have left in there?

thanks

Gwenz

 

Smaller fish can attack bigger fish, it's been heard, but I didn't know neons could get nasty. Would you have the option to isolate the neons from the danios with a temporary partition, to avoid too much upset/change on the fish and too much cost? You could always get a betta tank partition from the store, or build it yourself. On the other hand, why would they start getting really aggressive all in a sudden? Oh, hang on, I know my mollies get more aggressive the warmer the water. Could it be that neon behaviour is also sensitive to increases in temperature?

If it's not aggression, here's more really far fetched ideas: Could there have been a drastic change in the composition of your tap water? Something like metal poisoning? But again, you'd see signs of disease. They wouldn't just go dead. + your conditionner should bind any such substances.

Could it be that they are ALL dying of old age and it's a coincidence? Would be really surprising, but this is a peculiar situation.

How much does the temp fluctuate in a few hours? Like 2 degrees C or 5? Mind you, if they were too hot, they'd go on the surface all the time, and you've not really seen that behaviour, have you? + the way drastic temp changes would affect them would be through disease, and you've not seen that.

How are their bellies? Overly swollen or sunken? How do they eat? Still eating OK?

What about the food. Have you changed what you normally give them?

 

Would you have the option to isolate the neons from the danios with a temporary partition, to avoid too much upset/change on the fish and too much cost?

Not sure realy. Would that mean having to buy another filter for the other side of the tank? + I haven't seen any in my lfs.

Could it be that they are ALL dying of old age and it's a coincidence? Would be really surprising, but this is a peculiar situation.

Hmm, might be, but like you said its unusual. All I know is that cycling with fish shortens the life of the fish and when I first got the tank I didn't know about cycling so the fish went in the tank after having it set up for only a week.  :-[  Could this contribute to the situation?  ???
Also the Neons were'nt much smaller than they are now when I bought them, so maybe they were nearly adults anyway. ??? On the other hand the Danios were much smaller when I got them.  :-\

How much does the temp fluctuate in a few hours? Like 2 degrees C or 5?

Not much. It just starts out at like 26 'C in the morning which is the temp its set to and then its about 28 - 30 'C for the rest of the day. It gradualy rises until its night again when it drops back to 26 'C.

How are their bellies? Overly swollen or sunken? How do they eat? Still eating OK?

Their bellies seem fine. They eat fine as well until the last minute when its too late.  :-\  The neons always get less because the danios get there first but i've always made sure that they've all had some. Like, i'd distract the danios at one side with food and feed the neons at the other end.

What about the food. Have you changed what you normally give them?

Always fed them the same. Tetra Min flakes, Aquarian flakes, freeze-dried Bloodworms. I change between them a lot o give them a variety. Every once in a while as well I'll give them some of the Tetra Veg that I give to the guppies.

I find this whole thing weird. Why do they all die? ??? :'(

Gwenz

 

I thought you could have one filter/heater/airstone for both sides of the tank. Dave?

 

Just thought of something. This all started after one of the female danios dropped some eggs. they we're all eaten by the others. She was the 1st of the danios to die I think. then they all went one by one after that.  :-\ Don't know if it's got anything to do with it. But I just rememberd about the eggs.

Gwenz

 

Oh, do you have any idea what she died of?

 

Don't say grief that her eggs got gobbled up!

 

lol. Only thing I can think of for her was that the others chased her loads while eating the eggs and a few times she got crushed against the glass by them and they were nipping her a lot. :-\ I couldn't do much for her. She died later that day.

Gwenz

 

Wow, that doesn't sound pleasant. No disease though. Oh perhaps she had a disease and that's why they picked on her, but it's really guessing. Am wondering if the eggs didn't have the same disease, which got passed on to all the egg scoffers.

 

I thought you could have one filter/heater/airstone for both sides of the tank. Dave?

you rang? yea, that's true.

 

Yes, I did ring, and I'd like to log a complaint at how long it took you to reply. Your real life/forum life ratio is really slipping, mister!

 

Wow, that doesn't sound pleasant. No disease though. Oh perhaps she had a disease and that's why they picked on her, but it's really guessing. Am wondering if the eggs didn't have the same disease, which got passed on to all the egg scoffers.

it's possible that the eggs had a fungus and the fish that ate it developed some sort of internal parasites as a result.. i'm not sure how great a chance of that there is, but it's the only solution I can think of at this point, other than nitrite poisoning (but you would see some behavioral changes usually then.)

 

Yes, I did ring, and I'd like to log a complaint at how long it took you to reply. Your real life/forum life ratio is really slipping, mister!

a complaint, eh? where's that banishment to the netherlands button again? ! lol.. yes, I must admit it.. I often leave the computer for hours at a time. ! Kairi, the computer betta, is supposed to handle things for me but ever since she got a castle in her tank, she's too good for office work.

 

lol. Just did a water change in the tank, and replace the live plants with 2 silk plants and 1 plastic plants as the real ones were getting on my nerves. I'll test the tank tomorrow and see what the results are then.

Wow, that doesn't sound pleasant. No disease though. Oh perhaps she had a disease and that's why they picked on her, but it's really guessing. Am wondering if the eggs didn't have the same disease, which got passed on to all the egg scoffers.

it's possible that the eggs had a fungus and the fish that ate it developed some sort of internal parasites as a result.. i'm not sure how great a chance of that there is, but it's the only solution I can think of at this point, other than nitrite poisoning (but you would see some behavioral changes usually then.)

Hmm, never thought of this. I guess its possible, but what's the chances of that acctualy being the problem?

Gwenz ???

 

Hmm, never thought of this. I guess its possible, but what's the chances of that acctualy being the problem?
Gwenz ???

honestly, slI'm to nil .. it's a mystery to me at this point what is going on in that tank.. i'd even consider breaking the tank down, cleaning it all and putting it all back together, keeping the substrata and filter sponge wet throughout should the problem continue much longer.

 

Realy?! :-\ I suppose I have all the time in the world now until september to look after the tanks and do whatever. I'd like to redecorate the tank anyway so i'd probably clean it completely then.

I'm thinking now tho, can I add more fish (after my holidays) ?
Would it have to be more danios/tetras to make up the numbers of schooling fish or can I add something different?

Gwenz

 

well, the danios i'd get back to 6 to keep the nipping chances down. otherwise i'd just stick to 15" of fish however you wanted them.

 

cool thanks. ;D

Gwenz