Before Choosing Fish Before adding a new fish to the tank, it is important to consider several factors to be sure it has the best possible home. Tank Size: Many fish are social and will do better in a group. Consider the adult size of the fish and how many are needed for a comfortable group – smaller fish can be better accommodated in a smaller tank, but a larger tank will be necessary for bigger fish that need several companions. Also consider the space needed for aquarium plants, decorations and other equipment. Personalities: Some fish are peaceful while others are aggressive, and they all have different personalities. Some fish are very active and need more open space for swimming, while others prefer plenty of nooks and crannies for hiding. Choosing fish with compatible personalities will keep all the fish happier and easier to care for. Tank Care: Even easy fish have specific needs for water composition, temperature, plant preferences and cleanliness. Opt for fish with similar needs to make the tank easier to care for and keep all the fish happy and healthy.
