Help! Why are my fish dying?

[azaahp2]

Okay - so only two deaths. But still, two. And I'm really sad about my cory... so I want to make sure there's not something I can do to prevent any more...

Yesterday I discovered a dead young male guppy - about an inch or so. Tested water and parameters fine - ph 7.6 (normal for here), ammonia 0, nitrite 0, nitrate under 5.

It's a 160L tank and had a 20% water change and the cannister filter cleaned a week ago.

Tank contents: 8x male guppies, 5x sterbai cory catfish, 2x adult kribs male & female and they're not friends...! Plus plenty of tiny unidentified snails and some FW limpets.

Tank is planted with a sand substrate and numerous caves,

After the guppy died I thought oh well... that's guppies. But I hope he wasn't attacked by a krib...

Now the cory - they're pretty hardy apparently, and not so easy to come by! So I really want to know - was that chance, or is there something wrong? Could he have happened a fatal nip from one of the kribs (I put in algae wafers last night), or could it be disease? Too much food? Not enough food? Something else?

Is his tummy sunken in? Is that 'ribcage look' normal? (I have no idea of 'his' gender either, bwt LOL)

I've taken a couple of pics of him and would be really grateful if anyone has any thoughts on if there is something wrong. Thanks in advance!

 

[azaahp2]

Help! Not true! I just pulled out a snail trap (just a bowl with a piece of lettuce and a couple of stones to weight the lettuce) and there was another dead cory in it!!! ???

I'm guessing it was there yesterday...

Tested water again and parameters all seem happy still ... I think it's my two biggest cory's. Old age maybe? But I don't think they're even fully grown... what am I doing to them?

Here's the next one... hole underneath him...?

 

[FreshyFresh]

How long has the tank been setup and what is you frequency and volume of water changes?

What test kit are you using?

Given what you describe in stock, snails, etc.. I question your nitrate reading, but it could be 5ppm.

Has anything new been added to the tank?

 

[azaahp2]

Hey thanks for your reply!

Tank has been set up about 3 months. However I bought it second hand and didn't wash, let dry, or change the substrate. Cannister filter was purchased new and it's the first clean we've given it. I do water changes about 20-30% about fortnightly.

Test kit is API common one.

Yes I'm confused about the nitrates as well. My other tank is over a year old (and was also second hand - although we were none the wiser and cleaned everything when we got it...) and never shows a nitrate reading. I asked in the LFS the other day why I don't seem to have nitrates and their answer was that I probably do but as the lowest reading is 5ppm (as opposed to 0.25ppm for others) it just doesn't show on my tests... ?. Although, before I got my own test kit one of the times I got the water tested instore the nitrates reading was 40...

I'd begun to doubt my test kits cos never had an above 0 reading for Ammonia, Nitrites or Nitrates for either of my tanks... but in the last few weeks I've been cycling another new tank and I'm getting varying readings for all 3 in that tank... so it's not my kit!

As for adding to the tank, 2x males guppies were moved from that tank to my new cycling tank for about 3 days and moved back 2 days ago, a day before my guppy died.

Only other changes was about a week ago I took 3 male guppies and put them in my female guppy tank for a bout 3 days... then shifted them back.

I've seen my kribs chase off the guppies and cory's from their food once or twice, and the female can be pretty aggressive, but apart from that they usually just annoy each other!

But that cory's insides look nearly empty... is that because he might have been dead for a while... or is something else wrong? Or you think it could have been an ammonia spike...?

 

[FreshyFresh]

No nitrates is also I sign that the tank isn't cycled, but that being the case, you'd normally see ammonia or nitrite.

All I can add is make sure to completely follow API's instructions for the nitrate test. It's critical to shake bottle #2 vigorously for a full minute before you dispense from it and to shake the completed test tube for a minute. Very common for folks to do that particular test wrong.

20-30% WC every 2 weeks typically is not enough water being changed.

 

[azaahp2]

ok thanks, what would you recommend for water changes?

 

[FreshyFresh]

ok thanks, what would you recommend for water changes?

Once you know you have a fully functioning cycle, you typically do water changes so your nitrates never exceed 20ppm. They creep up daily. This all depends on your stocking level, the amount of food you add to the tank, if you keep plants or not, etc.

If your tap water contains 0ppm nitrates, your tank is at 20ppm and you do a 50% WC on the tank, this is only going to lower the tank to ~10ppm so you have to get a feel for it by taking readings.

 

[azaahp2]

All I can add is make sure to completely follow API's instructions for the nitrate test. It's critical to shake bottle #2 vigorously for a full minute before you dispense from it and to shake the completed test tube for a minute. Very common for folks to do that particular test wrong.

sooo.... you're right. I remember reading those instructions when I first got the kit, but it wasn't written on the bottle so I thought it wasn't important... I have retested nitrates, being sure to follow instructions properly - tricky to read the results as the 10ppm and 20ppm colours are so similar. The colour looked a little richer than 10ppm but not the 'red hue' like the 20ppm ... so I'm assuming 10ppm nitrates.

I never seen more than 3 cories and one time all day so I'm really nervous I have a third dead one somewhere... I'm going to do a water change and have a good look around the scape tomorrow.

Is there any chance they died of starvation? I feed once daily, and always make sure there's a good amount of food that falls to the bottom for the cories. Of course kribs are bottom eaters too though... and the cories always seem to find it last. I really don't want any more deaths!

 

[FreshyFresh]

I basically use the API master test kit nitrate test as a go, no-go gauge. Red is bad. Yellow is not so bad. LOL.

Sounds to me like your cory problem may be starvation. Corys need to be fed quality sinking pellets, wafers, blanched veggies, etc. They won't survive well on what ever flake food happens to settle. Flake food shouldn't really be settling out anyway. That's an indication you are putting too much in the tank.

 

[azaahp2]

I do feed food that sinks... bloodworms, shrimp pellets, algae wafers etc

I feed flakes about every 3 days and always let a good pinch drop 'under' the surface so it drops straight to the bottom because the kribs like it too. But usually put in algae wafers or something sinking as well.

Last night I'd fed tubifex worms which float, so put down some shrimp pellets as well, I kept scaring the guppies away from it till the cories had made their way around there but they didn't really seem interested, just kept sifting away at the sand... I'm so confused ?

I'll do a water change as soon as I can today and keep testing the water daily for the next little while and hope for the best.

Are there any other parameters that maybe I should be testing for?

Thanks!