Most first tanks are freshwater: heated tropical communities or, less often, coldwater goldfish. The pattern is the same — cycle the filter, match adult size, and ignore bowls. This pillar collects our freshwater species and the guides that belong next to them.
New to the hobby? Read beginner freshwater aquarium setup and how to cycle a fish tank. Looking at a 20-gallon kit? See stocking a 20-gallon tank.
Freshwater · Beginner
Betta splendens
Bettas are labyrinth fish that breathe from the surface, but they still need a heated, filtered aquarium — not a vase. A 5-gallon tank is a practical minimum for a single male.
Min. tank: 5 gal
Care notes →
Freshwater · Beginner
Paracheirodon innesi
Neon tetras are small Amazonian schoolers that look their best in a planted 10-gallon (or larger) tank with a proper group, dimmer light, and stable, clean water.
Min. tank: 10 gal
Care notes →
Freshwater · Beginner
Poecilia reticulata
Guppies are colorful, active livebearers for a heated 10-gallon (or larger) community — with one caveat: mixed sexes will produce fry, often lots of them.
Min. tank: 10 gal
Care notes →
Freshwater · Intermediate
Carassius auratus
Goldfish are coldwater carp, not bowl ornaments. Fancy strains need tens of gallons and strong filtration; single-tail commons belong in very large tanks or ponds.
Min. tank: 30 gal
Care notes →
Freshwater · Intermediate
Pterophyllum scalare
Freshwater angelfish are tall Amazonian cichlids. They need height more than a long, low tank — about 30 gallons and 18+ inches of height for a pair is a practical indoor start.
Min. tank: 30 gal
Care notes →
Freshwater · Beginner
Corydoras paleatus
Peppered corydoras are social, sandy-bottom catfish. Keep a group of six or more in a 20-gallon tank with sand, not gravel that can nick their barbels.
Min. tank: 20 gal
Care notes →
Freshwater · Advanced
Astronotus ocellatus
Oscars are large, messy cichlids for dedicated tanks. One adult needs about 75 gallons as a conservative minimum, powerful filtration, and an owner ready for digging, waste, and a long-lived pet.
Min. tank: 75 gal
Care notes →
husbandry
A fishless cycle grows beneficial bacteria before you add livestock. Test ammonia, nitrite, and nitrate until the tank can process a dose of ammonia in a day.
Read guide →
setup
A heated, filtered 20-gallon tank is a kinder first aquarium than a tiny kit. Cycle before you add fish, test your water, and stock slowly.
Read guide →
stocking
Inch-per-gallon is a myth. In 20 gallons, think in terms of adult size, schooling needs, waste, and swimming style — then stock less than the store display.
Read guide →