Yes, Siamese algae eaters are fin nippers. Despite being well-known for their peaceful and gentle temperaments, Siamese algae eaters will occasionally nip on the fins of other fish.
With this in mind, it’s best to avoid keeping long-finned fish with Siamese algae eaters.
With that said, there are precautions you can take if you insist on keeping Siamese algae eaters with long-finned fish. First, make sure the long-finned fish are top-dwellers. Second, provide plenty of space and avoid overcrowding the tank. Lastly, add lots of live plants, decorations, and hiding spots in the tank.
By doing these things, you’ll minimize the chance of your Siamese algae eaters encountering and nipping at the long-finned fish.