Nipped Geophagus. Culprit?

[spitz006]

75 Gallons (280 Liters)

many large peices of driftwood in a fluorite sand mix

1x Black Ghost Knifefish
1x geophagus steindachneri
1x geophagus surinamensis
2x bolivian ram
3x buenos aires tetra
4x silver-tip tetra
1x emporer tetra
3x kuhli loach
1x cory cat
1x oto cat
1x paradisefish
1x sparkling gourami


The both of the geophagus have nipped fins. Do you think it's the tetras? the knife fish? or are they doing it to eachother?

 

[bbortko]

I'm guessing its geo on geo, dont see the knife messing with them when you have so many smaller tankmates.