Description: 55 gallon containing an oscar, a managuense, and a parrot fish. All artificial plants, natural gravel, two whisper 30-60 hang on back power filters. Tank is very established (gravel and some rocks/decorations have been in constant use for 15 years). Fish were purchased as babies and grew in the tank.
Advice: Patience and research. Don't think that jamming a new aquarium full of fish will work, and always do the proper research for the requirements of the fish you intend to purchase and choose compatible tankmates accordingly. Never put a fish into an aquarium that is too small for the adult version of the fish.