Types of Fish for Freshwater Aquariums

Community Fish

• Community fish are generally peaceful fish that are not aggressive to each other. They tend to thrive better than other types of fish. When you first set up your tank, you need to put it through a nitrogen cycle to prepare it for different types of fish, and community fish are usually strong enough to use in the nitrogen cycle.
  Schooling fish are a particular type of community fish that like to swim together in clustered groups. When watching a group of schooling fish, you will see that they swim in unison. Since these fish prefer to be kept in a group, when you purchase schooling fish, you should always purchase them in groups of three or more. Common examples of schooling fish are tetras, danios and barbs.
  There are several types of catfish that help keep your tank clean and fall in the community variety of fish. There are over 70 species of Cory catfish; however, all of them are about 1 to 3 inches in size. They are constantly cleaning the bottom of the tank, making them ideal for a home tank. Cory catfish should be bought in groups of four. In general, Cory catfish need an average of 5 gallons of water each.
  Another common popular catfish for aquariums is the plecostomos. They clean algae from the sides of the tank and any decorations. They can grow considerably larger than Cory catfish and should be kept one fish per every 10 gallons of water.
  Another common community fish is the group of live-bearing fish. The female gives birth to live young instead of laying eggs. When purchasing live-bearing fish, you should always purchase two females to every male. This keeps the males from running the solitary female to death while he constantly tries to breed. Swordtails are an example of a unique live-bearing fish and are easily sexed. The males of the species have a long sword-like fin that sticks out behind them.

Semi-Aggressive Fish

• These fish are more aggressive than community fish and are known to attack smaller fish by nipping at their fins or chasing them. One popular species of semi-aggressive fish is the angel fish. These fish should only be kept with other semi-aggressive fish. When choosing an angel fish, purchase in pairs and choose young fish. Cichlids are territorial fish and should be kept with other semi-aggressive fish or community fish of the same size. Otherwise, the cichlids will eat the smaller fish. Mixing community fish with semi-aggressive fish can be successful, but the tank should be watched for signs of aggression. If you spy a fish bullying another fish, remove the aggressor immediately and isolate it in another tank. This will keep the rest of the fish in the tank stress free.

Non-Community Fish

• Non-community fish refers to any species of fish that should kept as a solitary fish and are generally large fish. One of the more common non-community fish is the Oscar. They are bully fish and will eat any smaller fish. A common treat for Oscars are goldfish. Since the Oscar can grow very large, even a small Oscar should be kept in at least a 75-gallon tank to allow for plenty of room to grow. Green terrors, as their name implies, are also bullies and will attack smaller fish. They are also very territorial and should only be kept alone or with other green terrors.