Lost 1 angelfish and 3 rummy-nose tetras

[rickf]

I've recently lost 1 angelfish and 3 rummy-nose tetras. They were all missing both eyes and tails were tattered. My tank consists of the following:

• Bala Shark (1x)
• Angelfish (1x)
• Dwarf gourami (1x male/2x female)
• Rummy-nose tetra (3x)
• Harlequin rasbora (6x)
• Panda cory cat (3x)
• Pencilfish (4x)
• German Blue Ram (1x)
• Rubber Lip Plecostomas (1x)
• Otocinclus catfish (2x)

It's a planted tank with driftwood and we had no issues up until about 5 days ago when we saw lost the angelfish. Water parameters are 0.25 ammonia, 0 nitrite, and between 20-40 nitrate. Yesterday we lost 2 of the rummy-nose tetras and 1 more today. I recently added the 2 otocinclus catfish about a week ago and the only aggressive fish I noticed was the male dwarf gourami. I moved him out of the main tank last night thinking he was the cause, but this morning there was another dead rummy-nose tetra.

Any ideas of what might be going on?

 

[rickf]

So I am thinking that the culprit is perhaps the now lone angelfish. I noticed its feces yesterday was an odd color (had some red/orange in it).

 

[absolutangel04]

Fish poo tends to be the color of the food they eat. Pretty much all food is a bit colored, so I don't think that is indicative of anything. Another note is that most every fish will eat a dead fish.
I have a guess who it is, but please let us know also how big your tank is, and how large some of your fish are. Are the angels and bala full grown yet?
Any other signs before death? Are these new fish, or are only your otos new? Fish will eat dead fish, so your deaths are not necessarily predatory in nature though I do agree that is seems that way. Just making sure we get all of your bases covered.

 

[rickf]

It's a 55 gallon tank. The otos are the only new fish. The bala shark is about 3 inches and the angel is maybe 2 inches.


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[absolutangel04]

Ok, good to know. My guess is your bala shark is doing it. I have seen situations in the past where balas turn nasty when the lights go out. I have doubts that it is a 2 inch angel, and their MO is not eating out eyes.
There is a chance that it is random die-off from some of the more sensitive species and they eyes are all being eaten by scavengers. But, my guess is your bala since everything has been happening in close succession.
It can be good to find decent rummies that don't die off within a matter of months, and young angels can be a bit sensitive, so there is a chance it s coincidence though.
Do you happen to have another tank you could try re-homing a him into to make sure?