After borrowing one of my fish to cycle the tank with he introduced three 3-inch pictus. After just a day of being wary they appeared to settle right in, cruising the bottom of the tank, eating a ridiculous amount of food and protecting their new territory by vigorously attacking the siphon tube once a week.
However, just one of them has begun acting very weirdly. He hovers in one corner of the tank, about halfway up, nose up, just moving his tail slightly to keep himself in that position. He'll return briefly to the bottom of the tank for food but returns straight to that position afterwards. This behaviour started about three days after they were introduced, and he does it constantly - all day, all night, for hours at a time. He only briefly acts normal for food and if one of the others bullies him out of the corner.
The only thing I can think of that causes listlessness and repetitive behaviour is water quality issues but it can't be that, I help him do waterchanges and water testing myself. The nitrates are always 20-30, temp is 23c, the ph value I can't remember offhand but I tested it just last week and it was normal, no drops or climbs since they were introduced. However bear in mind I'm a fancy goldfish keeper and might be missing something catfish-specific although it seems unlikely. He appears perfectly healthy except for hovering like a tard in the corner
Any ideas, anyone?
