Tiger barbs are known to be aggressive, to each other and to other fish, especially when kept in small groups. In larger groups, they usually calm down. So you may want to get some more of them. 90 gallons has plenty of room for a nice school, maybe 10 or more, depending on how many other kinds of fish you want.
aw y only one guppy? mayb u could also add an albino cory
Albino cories are also social fish that need to be kept in groups. So add a group of at least 6 if you decide to get some. But halfmoonplakat is right that some bottom dwellers would be cool. Maybe a group of cories or kuhli loaches.
Some important things to keep in mind, to research, before buying new fish:
Do they all share the same temperature requirements? You don't want coldwater fish mixed with tropicals, because there's no one temperature where they can all be happy.
Can I get just one of this species, or does it need to live in a group? Many of the most common fish in the pet stores need to be kept in groups. They are called shoaling fish or schooling fish. Because of their social structures and need for companionship, they will be stressed and prone to disease if kept alone or in groups that are too small. A minimum of 6 individuals is usually recommended. Fish that need to be kept in groups include barbs, tetras, cory catfish, rasboras, danios. Also, platies, guppies, and mollies do well with at least or two others of the same species.
Will this new fish get along with my old fish? For example, many people don't mix cichlids with other tropicals (but I think your angels are ok).
