So, to help you out, here are five fish suitable for 20-gallon aquariums. Diet: Omnivore Size: 2.5 inches Lifespan: 5 years ...

5 years Water Temperature: 72 – 82 Fahrenheit Ideal pH: 6 – 8 Minimum Tank Size: 30-Gallon Kicking off our list of the best catfish for freshwater aquariums is the distinctive bristlenose pleco.