[Axilleus]

I now have two black-skirt tetras who have torn fins, one with the tail completely nipped off. Water parameters in their 30 gallon tank (with 6 black-skirt tetras and 6 cories, all about an inch) are 0 ppm ammonia, 0 ppm nitrites, 0 ppm nitrates. The light was off for about a week while I ordered a new bulb online, and that's when this damage happened, although it may be so extensive just because I didn't notice. Now the two damaged fish are in a 10 gallon that formerly housed my betta (who has been relocated for the purpose) which has parameters of 0 ppm ammonia, 0 ppm nitrites, 10 ppm nitrates. I added aquarium salt (1 tablespoon) to the 10 gallon. Both tanks are at about 78 degrees.

One of the black-skirt tetras (the one with no tail) is not eating, but they're both swimming fine.

So: Are the white spots related to the injury? Is this definitely a fin nipping problem, or is it possible it's crazy aggressive fin rot? And what can I do to heal the fish/ stop them from doing this to each other?

 

[Pearl2011]

If it had progressed so quickly then t is probably a combination of the two. i don't think the light as too much of a contributing factor, but maybe it stressed them out?

The white spots are probably ich, and the salt in the water will definitly help. Clean should help them recover faster ad cleaning it clean will prevent these issues from arising again.

 

[Axilleus]

Update: Both fish are now eating and their fins have mostly regrown. The white dots are gone. I would like to know how to prevent aggression like this in the future, but this episode turned out fine.