Originally Posted by Tsquad
So I have 8 guppies and 6 white skirt tetras in a 55g. I have had issues with fin nipping since I got them 6 months or so ago. I just moved them from a 20 tall to the 55g a month or so ago, hoping that more room would help, but it has not. Is there anything I can do to help stop this without getting a 3rd tank to keep the white skirts in?(have a gold fish in the 20)
Plant the surface of the tank really well. Floating plants like Water lettuce, Hornwort, Water sprite, Anacharis and Pennywort will grow quickly floating up close to the light source and provide hiding places for bullied fish. Floating plants also make aggressive fish feel more comfortable in their surroundings. Any fish with elaborate fins like male Guppies are a target for aggressive fish.
As for Goldfish, the species isn't tropical. They prefer much cooler water, around 65 degrees. I keep tanks of fancy and common Goldfish and don't use a heater in the tanks. Your tropicals will need water at least 10 degrees warmer, if you want them to stay healthy. The size difference alone would be an excellent reason for not putting Goldfish in with tropicals.