[Glaneon]

I have a 20 gallon grow out tank - tank has been doing fine since Nov 13th (used established filter/media and water from my 125 gallon)

These fry (F2, Pseudotropheus Kanchedza) have been in this tank since December 16th. They were in a fry basket at first the left to free roam once they wouldn't get sucked up the intakes.

Doing 50% water changes every 4 days (on average, some 2, some 6).

No issues at all until Friday (2 days after last water change). Checked ammonia, 0.
All started acting lethargic, not coming up for food, etc. Lost 1. I did a 75% water change and added the buffer recipe as usual.

I removed 3 of the most lethargic to my hospital tank. This morning 1 of those had died in that tank.

This morning, in the 20 gallon grow-out the rest appeared worse than Saturday. Found 2 dead. Moved the other 9 or 10 left alive to the hospital tank. It looks like 1 isn't going to make it until this afternoon.

I tested my tap water, no chlorine (normal, I have a whole-house filter; last water change I did was also done on my 75 & 55, no problems in there). Tested the tank water, looks like expected after a 75% water change & adding recipe. (negligible Nitrate, 0 Nitrite, 0 ammonia, 300KH, 300GH, 8.4pH).

I had 17, down to 10 now I think

They've always appeared to have reddish gills but I think that's normal for them.

 

[DJRansome]

Awww, sorry for your losses.

I've never had this happen with mbuna fry. But try changing the water in the main tank so nitrates are down to 10ppm. And then use the "main tank" water for the fry tank water change.

 

[Glaneon]

Nitrates are staying below 5ppm, always do. (in the grow-out tank)

Unfortunately water from the main tank nitrates are around 15-20ppm currently. (I've held off changing water on the main tank until I figure out what's going on). But with a water test on my tap, I didn't see anything wrong and it's what I've been using for everything, 7 aquariums, only these guys are having issues.

Thanks for the response DJ.

 

[DJRansome]

Since the tests are not showing you anything that is likely to cause the problem...

But the main tank water seems OK for them...

I always suspect whatever is harming the fry is something I cannot measure. I had a similar problem with cyp fry...fine until the water change.

I know that breeders of Tangs that are unhappy at water change time use this technique.

I don't have any other ideas.

 

[GTZ]

Fry tank has always been ~8.4pH? I would add that my elongatus fry are always red around the gills until they get about 1.5".

 

[Glaneon]

I guess I meant I've been doing 50% water changes in this particular tank, using tap water + recipe since they've been in the tank. I only took the original tank water when I first filled it up back in November.

About 3 weeks ago I added an "ornament" - just the top ( http://www.walmart.com/ip/HOMEDICS-Envi ... n/15842530 ). They seem to really like the little cut outs for hidey holes. No issues at ALL until Friday - I mean, night & day difference. I could feed them a little 3-4 times a day, always rushing to the top to get the NLS grow.

Yeah, fry tank always kept at 8.4.

 

[Glaneon]

Update:

I looked at my Fish Disease guide that came with the Maracyn & Maracyn II I bought a while back for another fish issue. It recommended Maracyn II (among other things).

One note: The water in the hospital tank was not at the pH for my cichlids so I started raising it one 1/4 tsp at a time, it's around 8.0 now. I also added some epsom salt to get the GH up. It's at 300GH now.

I did the initial dose of Maracyn II and within about 2 hours they've started acting more normal (still not as zippy as usual). Even the one I thought wasn't going to make it appeared to be doing better.

This morning I would put them at 80%. (whereas Saturday I would have said 20% for most and 5% for the one I thought was going to die)

I have today and 3 more days of dosage on the Maracyn II but I thought posting results may help someone else.