Dying Fish

[James007]

I bought a 25 litre tank 2mths ago. It is one with a built in heater, lamp and 3 stage filter in the hood. I put in the treated water (plus a small castle, fake rock and pebbles) and then a week later put in 4 small plants. 2 weeks after that I put in 6 neon tetras, one of which died within days. 4 weeks later I added 3 platys, 2 shrimps, a glass catfish and a male fighter. All was going great for a week. I was changing 15% of the water every 2 weeks, feeding twice a day (flakes and dried bloodworm) and using the lamp for 2 hours a day.

However I went home last night and the catfish and 2 tetras were lying dead on the bottom. The other fish looked quite ill and drowsy. The other 3 tetras died within the hour. I changed 25% of the water and pulled out one of the plants that had some dying leaves on.

I ran tests on the ammonia, nitrate, nitrite and Ph and they looked to be within acceptable levels with only the nitrate of any note. The constant tank temperature has been 25 degrees.

The fighter, 3 platys and shrimps have made it through the night but still look drowsy and on their last legs.

Whilst I cannot figure out what has happened: I may have been overfeeding them. Some plants do have dead leaves. The water in the tank is quite smelly/musty.

I have read through several books and followed the advice from the shop.

Can anyone explain what has happened, how I fix it to save the remaining fish and prevent it happening on the future?

 

[fishwatcher]

What are your actual test results?

 

[Annastasia]

It seems like your tank is pretty overstocked, which can cause bad water quality. Neon Tetras are very sensitive to that, which may be why they died. And bad water quality is probably also why the other fish died, or aren't looking so good. Unless, are the fish showing any other symptoms?

I'd only keep the fighter, and possibly the shrimps in there. Is there anywhere else you could put the Platies?

I'd also be interested to know the test results.

 

[dream250578]

I have been told by my lfs that you should only add neons to mature tanks ie. approx after 6 months. Might be wrong though

 

[James007]

Thanks for the response Fishwatcher/Annastasia,

I am in work at the moment and have the test results at home. I will confirm these tomorrow although I can remember the PH was a little high at 8.5.

I do not have anywhere else to put the Platys as I am a beginner and this is my first tank! I do not have a second filtered/heated tank.

The only other symptoms I could point to would be a possible 'whitening/graying' under the front of the fighter and a possible dicolouration around the gills of the Platys but his is fairly minor if anything.

The fighter kept hiding in the small castle and then dashing out to the surface as if to take a gulp of air before returning to the castle. The Platys seems to 'rest' on the surfaces or float at the surface and are uncharateristically still.

I did have quite a few snails in the tank a few weeks ago (must have come in on the plants) however these seem to have disappeared now.

I can't understand how this has developed in about 5 hours from what appeared to be a healthy tank to a 'morgue'. The only changes I have made recently are the change from daily feeding to twice daily and to include dry bloodworm. I have also recently changed the 'bacteria sponge sachet'.

 

[dwarfgourami]

Sorry to hear about your your deaths. The important test results are not actually ph at this stage but ammonia and nitrite.

Basically, your tank (25 litres=c. 6 gallons) is really too small for anything but a fighter. It is very likely that your fish have died from overstocking. There are frequent threads on this forum where fish deaths occur under similar circumstances, though the test results appear normal. On a small tank like this you probably need to change water more frequently than every other week, anyway.

As Annastasia said, you must remove the platys. Offer them to the lfs for free if you have to; it is still better than seeing them die. And you may need to do several water changes over the next few days.

 

[natron1968]

It sounds like to me your tank hasn't cycled yet. 8.5 pH is not good. Do water changes to bring it down to around 7. Make sure to dechlorinate with something. It can take 6-8 weeks to cycle a tank - it's happened to me. I would do 50% daily water changes until my parameters looked alright.

 

[fishwatcher]

Also, you said that you changed your feedings from once a day to twice day. It may be that there is more food left to rot and cause ammonia/nitrite problems, as well as being overstocked. Definitely test your amm, nitrite and nitrate readings, and keep doing good water changes. When you say that you changed the sponge, do you mean you took out all of the filter material that was in/on your filter? If so, you may have removed all the good bacteria, basically setting your tank back to square one. I am still fairly new at this too, so make sure you listen to the others' advice before mine. But this is what I've learned so, so it should help! Good luck and keep us posted!

 

[dwarfgourami]

quoting natron:

"8.5 pH is not good. Do water changes to bring it down to around 7."

That would depend on the ph in his tap water. My tap water is 8.4, so no amount of water changing in the world would bring that down to 7; I'd just be adding more of the same. Most of southeast England has very high ph- and successful fishkeepers. Anyway, a high ph is not necessarily so much of a problem (my lfs keep all their fish in local tap water); the most essential thing is to keep it stable ie not to fiddle with it unless you really are an expert. With a high ph there will be certain things you cannot do, like breed neons probably, but it shouldn't kill fish unless they are brought into it suddenly from a very low ph.

Water changes are essential at this stage because of the cycle, not because of the ph.

 

[James007]

Thanks again for the feedback.

The fish were similar last night when I got home. I went to my lfs to see if they could help. They re-ran my tests with the same results:

PH - 8.5 (this is the same as my fresh tap water - I live in the North West)
Ammonia - 0
Nitrite - much closer to 0 than 0.1 (almost clear)
Nitrate - closer to 0 than 10mg

Hence they did not feel this was the root of the problem.

Given the size of my tank, the built in filter provides a feeble trickle back into the tank so they suggested that there may not be enough oxygen getting back into the water. They suggested getting a separate air pump.

Given the possibility of overfeeding and the dead leaves etc from the plants they also suggested a gravel cleaner/hoover.

I purchased both. I fitted the air pump with air stone, cleaned the debris from the gravel and rang another water change.

The results were almost immediate and there was a slight improvement in the fish behaviour. This morning they are clearly nearly back to themselves and are feeding again.

Fingers crossed this was the problem.

 

[James007]

NB - Sorry Fishwatcher - I replaced the carbon sachet but not the sponge it sits on. I was advised this would remove the bacteria completely whereas I just needed to replace the sachet that tops it up.

 

[fishwatcher]

Keep an eye on them, just in case, but it sounds like you may have solved the problem! That's great!