The aquarium kind of catfish, that is. I'm something of a fish fanatic, as anyone who knows me can testify. I have 5 aquariums running at the moment, with mostly catfish and loaches. Some of my favorite ones are plecos, a group of catfish from South America with often striking coloration. For me it wasn't enough to have them in my aquariums - I made some from yarn as well. Yeah, I'm a bit weird that way.
I first knit the huge one in the photo, making up the pattern as I made him. This one is based on a catfish called Snowball Pleco, currently known scientifically as Baryancistrus sp. LDA 033. (Many of these have not yet been scientifically described, hence the number and letter combination to keep track of species.) You'll find photos of this beautiful catfish on this page of Planet Catfish. How well did I do? ;) He was knitted from black yarn (mix of wool and polyamide), stuffed with synthetic fill and the white spots were embroidered on. More photos of him can be seen in this deviantArt entry.
The smaller catfish were made in the same way, though with crocheted fins, using the Starlight Bristlenose Catfish (Ancistrus dolichopterus, L183) as the model. Photos of that beauty can be found on this page. I have close relatives of this species in my own aquarium, but mine lost the white fringe of the fins as they got older. They still have the white spots on a black body and look great, in my humble opinion.
The big pleco is 65 cm (~25 in) long and does a good impression of a comfy pillow while lying on the bed. The smaller ones are 15 cm (6 in) and 12 cm (~5 in) long and are available through my Etsy shop. I don't think you want to pay me as much as it would take to make you a big one, however. ;)
Small Starlight catfish
Slightly bigger Starlight catfish