I have a quick question.... I have a Fantail Goldfish (male) appprox 4 months old that swims around without extending it's dorsal fin. It will raise up a hair and then just lay on the fish's back. Any thoughts of why this may be happening? It's a 30 Gal Tank, plenty of filtration and additional air bubbles, live plants, loose gravel. Ph, Nitrate, Nitrire, levels are excellent. No chlorine present in any of the test strips. Monthly tank cleaning regimen.
Population of tank: 3 Fantail Goldfish, 2 Neon Tetras, 1 X-Ray Tetra. No fighting, they all swim and play together, no aggressive behavior at all from any of the fish.
Thanks for your time and help!
A new wrinkle ..... the Fantail that has the fin problem has now developed a dark verticle line on both sides of it's body where the tailfin and body meet. My wife and I are very very new to fish and aquariums but so far (in the last year or so) we haven't lost any fish. Any help and insight is appreciated. I'm trying to grab a photo of the fish so i can show you exactly what I'm talking about. Thanks, again.