Since moving into my 2000L tank the black aro has been growing fairly steadily, from ~12" to 18-19" since July. One thing I've noticed is the strange growth of his fins, more so the dorsal, tail and anal fins. It is as if the rays have been growing faster than the membrane between them. The water is good (very low hardness and TDS, pH ~6.8-7, 26-7C, 0 ammonia and nitrite, <20ppm nitrate), and the finnage of the other fish, including Geophagus and angels, is fine. I was wondering if the membrane would "catch up" to the rays, if it were caused by a growth spurt, but it appears to be becoming more exaggerated. The fish appears healthy, eats well (shrimp and hikari sticks), and the other fins appear unaffected. Any suggestions???
September;
Yesterday;
September;
Yesterday;