Nipping or Fin Rot?

[SJ725]

I have a 55 gallon stocked with:
8 neons
1 honey gold gourami
6 glofish
2 corydoras
3 Siamese algae eaters
5 white cloud minnows
The tank has sand substrate and the decorations include live plants, a madrona branch, and a couple of rocks. The parameters are as follows:
Temperature 78°F
Ammonia 0
Nitrite 0
Nitrate 5ish
pH 7.4
My corydoras, and ONLY my corydoras, are missing chunks of their fins. Is this a case of fin rot or nipping? Are my other fish in danger?

View attachment 1470442069967.jpg

 

[sugarraycrafts]

If it was fin nipping I would be looking toward the siamese algae eaters as they can get territorial, however it kinda looked like fin rot to me. I imagine with most animals, certain species will be more prone to certain diseases then others. Are any of the fish new additions?

 

[SJ725]

The algae eaters are new; I'm pretty sure this started before I got them.

 

[fish fanatic centeral]

are they eating

 

[lloyd378]

Looks like nipped find to me...... With your stock list I would guess the culprit to be the honey gourami.

I once had a tank full of corys and noticed the same thing. After watching the tank with the lights off in the room I found that my cichlid fry. 1-1.5 " were biting them like crazy ( ended up removing corys )

 

[SJ725]

Thank you

 

[SJ725]

are they eating

Yes

 

[fish fanatic centeral]

well then it is probably not fin rot, plus when it is fin rot you would most likely see a fungus eating away at the fins.