Sudden Deaths

[rabidric]

Hi

Recently we've suffered a couple of sudden and inexplicable deaths in our tanks. What's odd is that the fish are swimming around fine when we go to bed but dead when we get up. Different tanks and different types of fish. In the 200l we had three denisonii but now we're down to two. In the 400l one of our plecs just gave up the ghost, and it was only a small one so not old. None of them were "new" so it's nothing like that. The water stats are fine and all the others in both tanks are fine. We keep a variety of different species and it's not even the most sensitive ones that die.

Given that we've exhausted our ideas as to why it happens do any of you have any suggestions or suffered similar occurences?

Thanks

R

 

[CFC]

The first thing i always look to when fish start dying for no reason is oxygen levels, particularly if the tank is planted and stocked with medium/large fish and especially if like your dead fish they are ones known to have high oxygen dependencies. I have witnessed with my own tanks in the past when i kept plants that after a couple of hours of the lights going out that the fish would start to hang near the surface or line themelves up in the current, i eventually worked out that when the lights go out plants stop producing oxygen and actually start using it from the water instead, thus lowering the available O2 content in the tank and starving the fish of oxygen.

By the way stock lists shouldnt be in your signature so i've removed it to your personal profile.

 

[rabidric]

Thanks for the response. I'm not sure about the oxygen levels as both of the fish mentioned were smaller examples of their species. My green phantom is at least twice the length of the one that died (can't remember what type he was but he was only 50mm at most) and the denisonii was the smallest of the three.

Thanks for tidying up the signature too. Maybe I should take a look at the do's and don't's but being a bloke I don't generally do instructions until it goes wrong.

Thanks again R

 

[TribeOfShroom]

The first thing i always look to when fish start dying for no reason is oxygen levels, particularly if the tank is planted and stocked with medium/large fish and especially if like your dead fish they are ones known to have high oxygen dependencies. I have witnessed with my own tanks in the past when i kept plants that after a couple of hours of the lights going out that the fish would start to hang near the surface or line themelves up in the current, i eventually worked out that when the lights go out plants stop producing oxygen and actually start using it from the water instead, thus lowering the available O2 content in the tank and starving the fish of oxygen.

By the way stock lists shouldnt be in your signature so i've removed it to your personal profile.

I'm guessing that keeping an airstone active through the night and good surface aggitation will help prevent an oxygen depleation.

 

[rabidric]

All our tanks have airstones on the go at all times and the spray bars are set to agitate the surface. I've only seen the fish at the surface once and that's why we installed the airstones.

It's very frustrating when you spend the time and take the effort to give them the best you can and then they still die! How ungrateful can you get?! I'd understand it more if I neglected them but I don't.

R

 

[jarcher1390]

ive lost 3 fish size 4" one of them was rare and the other were just spectacular down to the their color like my banded rainbow fish due to depleted oxygen levels i put the pump nearer to the surface to increase flow which has seemed to help a lot if i was to put any large fish back into i would put an air stone in as well
A great tell tail indication is rapid gill movements when they are resting.
Jonny
Edit: Spelling

 

[rabidric]

Yeah I learnt that lesson ages ago and as I said before airstones on the go constantly and the spray set to break the surface. I don't run the tanks too hot as I know that can reduce the oxygen levels too. None of the fish seem to be breathing rapidly or to be sluggish or inactive or show any other signs of being ill in anyway.

I just wish I knew so that I could prevent it

R

 

[rabidric]

Since we had the sudden deaths in the tanks we have found that one of the heaters in each was cracked and letting water in. One recently showed signs of rust internally but the other nothing obvious, it was only when we moved it that the two pieces became obviously separated. Different makes and none of them were ever run without water we always made sure they were unplugged or pushed well down during water changes. The indicator lights came on so I guess they were still working. Here's the question - would the leaking electricity have presented a health issue to the fish? Were we in danger of frying, well boiling, the fish or injuring ourselves? Anyone else had anything like this, and if you have any idea what caused it?

Thanks

R