Most people start with smaller aquariums to keep nano fish like guppies and bettas. But have you ever thought of moving up to the next weight class? 29- and 30-gallon (110–114 liters) aquariums are some of the first sizes that allow you to start getting medium-sized species. They also give you the extra space to design more elaborate aquascapes or biotopes. Learn about our top 5 fish stocking ideas that fit in this popular category of tanks.

1. The South American Aquarium

The Amazon rainforest is home to many beautiful species, so why not create an environment that highlights this biologically diverse corner of the world? In this setup, aim for softer water with low GH, pH from 6.8–7.4, and warmer temperatures around 80–82°F (27–28°C). For the bottom level of the tank, pick your favorite species of Apistogramma dwarf cichlids (or apistos) and get a male-female pair that will hopefully breed for you. Because they can be a bit shy at first, you may want to provide aquarium plants for cover, catappa leaves to tint the water, and apisto caves for egg laying.

A school of cardinal tetras can act as dither fish to help the apistos feel more comfortable and ready to spawn. These stunning tetras feature bright blue and red stripes that run horizontally down their sides and will actively swim back and forth in the middle of the tank. Finally, as long as you have a tight-fitting lid to prevent jumping, you can add a school of hatchetfish to fill in the top stratum of the aquarium. This triple-layered arrangement is well-suited for taller aquariums, like a 29-gallon tank that stands 18 inches (46 cm) tall.

Left to right: cockatoo dwarf cichlid (Apistogramma cacatuoides), cardinal tetras (Paracheirodon axelrodi), and common hatchetfish (Gasteropelecus sternicla)

2. The Angelfish Breeding Project

Breeding fish is always exciting in the aquarium hobby, and a 29-gallon tank can open up many new possibilities to try. Angelfish are not very hard to breed, so get a nice-looking male and female to pair up in this species-only setup. They like to lay their eggs on vertical services, like a piece of slate leaning against the wall, the filter pipe, or a large Amazon sword leaf. It may take the angelfish a few tries to figure out that they should not eat their own eggs, but over time, they  usually learn to raise up their own offspring.  Watching the parents carefully corral a cloud of babies can be a very rewarding experience for you and your family to enjoy. Feed the fry a variety of foods like baby brine shrimp and Hikari First Bites, and be prepared to buy additional aquariums to house the growing brood. For more details on angelfish, read our full care guide.

Gold angelfish (Pterophyllum scalare) protecting a clutch of eggs

3. The Unheated Aquarium

Cold water fish are cool because they can live in lower temperatures, whether it’s in a chilly office building, basement, or living room tank with no aquarium heater. Longfin rosy barbs are one of our favorites because they are relatively peaceful for a barb and will even nibble on algae in your fish tank. The males tend to be reddish in color, while the females have a golden sheen. Get a school of four to six fish because they are a very active species and will eventually grow to 3.5–4 inches (9–10 cm) long. For the bottom of the tank, try a group of salt and pepper cory catfish, which is a Corydoras species that can live in cooler waters. Fill in the scenery with live aquatic plants, and enjoy this simple but show-stopping work of art. For more ideas on coldwater species, read our top 10 list.

Longfin rosy barb (Pethia conchonius) and salt and pepper cory catfish (Corydoras paleatus)

4. The GloFish Tank

GloFish are an eye-catching staple at pet stores because of their shocking neon colors that glow under blue lighting. If you want a kaleidoscope of activity, pick either GloFish tetras (black skirt tetras) or GloFish barbs (tiger barbs) as your schooling fish. They both grow to 2.5–3 inches (6–8 cm) in size, so start with a group of six to 10 fish of the same species. For a 30-gallon aquarium with a longer, 3-foot (91 cm) footprint, you may be able to add one GloFish shark (rainbow shark) as well. (Of course, if GloFish are not your cup of tea, you can always get the normal-colored versions of these species instead.) Since most of these fish are semi-aggressive, add plenty of tall decorations to block line of sight and provide cover for weaker individuals. To learn more about GloFish and where they get their fluorescent hues, read the full article.

GloFish tetra (Gymnocorymbus ternetzi) and GloFish barb (Puntius tetrazona)

5. The Fancy Goldfish Aquarium

Many beginners are surprised to learn that their pet goldfish can grow up to 6–8 inches (15–20 cm) long, which is why they should skip the small glass bowl and upgrade to a 30-gallon aquarium. Because of the fish's larger size, we recommend choosing only one fancy goldfish for this setup. Their egg-shaped bodies and flowy double tails tend to make them slow swimmers, so use gentle filtration like sponge filters. Also, water quality issues can arise from their heavy waste load, so do not add too many tank mates unless you plan to upgrade to a 40- to 55-gallon tank. These hungry hippos are notorious for nibbling on or uprooting aquatic plants, so look for goldfish-safe plants to help purify the water and beautify your aquarium. Finally, keep the water cooler at 50–70°F (10–21°C) for optimal health. Read our care guide for more info on their husbandry.

Fancy goldfish (Carassius auratus)

For more fish stocking ideas and inspiration, check out our article on 7 Popular Fish You Should Try in a 20-Gallon Aquarium.