The 15 Best Types Of Freshwater Aquarium Catfish May 13, 2021 · Bristlenose Plecos get about 3 to 5 inches long. While not the biggest aquarium catfish around, they still need plenty of room to swim around. A 25-gallon tank is recommended. The fish are very hardy and can adapt well to many environments. They do best in waters that are between 60 and 80 degrees. 5. Bumblebee Catfish