This is an algea eater. His name is Catfish. Currently, he's been living in a 10 gallon tank with a few guppies. I kind of feel bad for him (her) because the 35 gallon tank I raised him in sprung a leak and he's had to adopt to his current cramped quarters.
He's a big sucker. He's quite friendly and doesn't spook easily unless he's being gawked at by an observer. But I can tap at the glass where he suctions his mouth and he will stay put. Even while I siphon the water for filtration with a tubular contraption that works much like a vacuum cleaner -- and nobody likes the way vacuum cleaners stir everything up -- Catfish will still remain still as I vacuum underneath him. That's bravery.
He has weird looking pupils on his eyeballs. They truly aren't your regular, everyday eyes. Perhaps one day I will show them in another entry. In this picture he has just finished making a request for replenishment of the water level, so here I am waiting for the dechlorinating chemicals to fully activate in the bucket of water I've prepared.