Adding Freshwater Fish

Generally speaking, 4-6 small fish can be added to a new aquarium (10 gallon aquarium).
Types of fish recommended for a new aquarium: Barbs, Swordtails, Danios, and some Tetras. These fish withstand the nitrogen cycle better. Types of fish not recommended for new aquariums are neon tetras, cardinal tetras, glo lite tetras, angels, and guppies. These types of fish do not withstand the nitrogen cycle well.
Jack's codes all fish. Follow the A, B, C & D coding when selecting compatible fish for your aquarium.
Mix fish of comparable size.
Live bearers - should purchase 2 females/1 male.
Schooling fish - should purchase 3 or more at one time.
Cory Catfish - should purchase 1 catfish for every 5 gallons of water.
Plecostomus - should purchase 1 for every 10 gallons. (Add after the aquarium has completed the nitrogen cycle.)
Sexing live bearing fish - males have a pointed fin underneath the belly area. Females have a round fin underneath the belly area.
Sexing egg laying fish - more difficult to sex; sometimes by color, body shape or fin shape.