Here is a video featuring six 4-line Pim catfish that we currently house in 4500 gal. They are 8"-10" (eyeball estimates). These are all Pimelodus blochii or of the blochii type, which, AFAIK, is characterized by a large black spot at the base of their dorsal fin.
Four of them look more or less like the usual blochii and are rescues. Another I bought for $30 about 4 years ago from Aquabid that claimed it was P. maculatus, which of course it wasn't as it still had that black spot of the blochii group that maculatus doesn't have. Still, it's body spotting pattern is different, crisp (it was different when I was buying it too at 3" with large black spots) and you will see in the video that it differs from the rest of the blochii, albeit other than the coloration, it looks identical. With years its spots became smaller w.r.t. to the body size, crisper, and 100x more numerous.
The last one is a survivor of a group of 3 that I got 6 years ago that I thought were Pimelodus tetramerus because of their more pronounced 4 lines on each side (true today and back then too at 2"). Consistent with this tentative ID is the fish's size too as it is clearly the smallest of the group at about 8" and has not grown any in a couple of years. The other two fell victim I suppose to one of my jau catfish a long time ago in a 500 gal pond.
Four of them look more or less like the usual blochii and are rescues. Another I bought for $30 about 4 years ago from Aquabid that claimed it was P. maculatus, which of course it wasn't as it still had that black spot of the blochii group that maculatus doesn't have. Still, it's body spotting pattern is different, crisp (it was different when I was buying it too at 3" with large black spots) and you will see in the video that it differs from the rest of the blochii, albeit other than the coloration, it looks identical. With years its spots became smaller w.r.t. to the body size, crisper, and 100x more numerous.
The last one is a survivor of a group of 3 that I got 6 years ago that I thought were Pimelodus tetramerus because of their more pronounced 4 lines on each side (true today and back then too at 2"). Consistent with this tentative ID is the fish's size too as it is clearly the smallest of the group at about 8" and has not grown any in a couple of years. The other two fell victim I suppose to one of my jau catfish a long time ago in a 500 gal pond.
