black ruby deaths

[dax29]

I've got a 29 gallon tank with a dwarf gouramis, a blue ram, 3 YoYo loaches, and three clown loaches. The loaches are 2" or less. I also have (or had) 7 black ruby barbs. These have been very enjoyable and seem healthy, don't nip as much as tiger barbs, and have grown considerably in the past several months. However, I've lost 2 in 2 days. I noticed one yesterday that was just kinda floating around the tank being pushed by the currents. I've got a Tetra Whisper 30 and an Aquaclear 200 for most of my filtration. I also use a [acronym:df8faf104c="Under Gravel Filter"]UGF[/acronym:df8faf104c] without the powerheads. I do 30% PWCs every 7 - 14 days. I checked my water and the ammonia and nitrite were not detectable. Nitrate was 30 - 40 [acronym:df8faf104c="Parts per Million"]ppm[/acronym:df8faf104c] 2 days ago and I did another 15% [acronym:df8faf104c="Partial water change"]PWC[/acronym:df8faf104c] since then. When I turned the light on this morning I saw another dead black ruby barb. Now I'm at 5 black rubies. The odd thing is that I don't notice anything wrong with these guys until they show up on the bottom (except the one that was floating around). I'm pretty good at observing things wrong, at least while I'm watching them. They all seem to be voracious eaters and were last night when I watched them. I figure if a fish doesn't eat and compete for food they probably don't feel too good. Now these fish don't seem to fight much, I don't see any tattered fins, or anything that sends up a red flag. I do know that I've got too many males. Actually, I've got only 1 female that I can identify. Could all the males be fighting at night when I'm not watching. I purchased these fish young, so now that they are older and getting more serious about the birds-and-the-bees, could they be fighting more? Should I buy another female if I can sex it at the [acronym:df8faf104c="Local Fish Store"]lfs[/acronym:df8faf104c] tank?

[TankGirl]

I do not think the gender is playing a role here, but there must be some sort of infection that has gone undetected afflicting them. When quarrels over females or rank arise you will definitely see the fish look "picked on" and usually you will witness the activity.

Since it is only the barbs afflicted, I would remove the remaining ones into a quarrantine tank for observation and possible treatment. They will be easier to watch there, and hopefully something will make itself obvious. Your water quality does not appear to be an issue at all.

[dax29]

Well I haven't seen any losses since the last post. No ill behavior. Thanks and I'll keep my eye on them.