5 Best Fish Tank Ideas for a 40-Gallon Breeder Aquarium

Because of its dimensions (91 x 46 cm x 41cm) the 40-gallon breeder tank is very popular, it measures 36 inches in length, 18 inches width, and 16 inches height. Other 40-gallon tanks have a more rectangular base, but the 40-gallon breeder tank has a deeper base without being too tall so that you can easily reach inside to clean the aquarium and catch fish that you have bred. The 18-inch width also lets bigger fish to turn around more easily, making this one of the first footprints that allows you to keep either a larger solo specimen or community of fish. Keep reading to learn about our top 5 fish stocking ideas for a 40-gallon breeder tank.

1. The Flowerhorn Tank

Flowerhorn cichlid

This hybrid New World cichlid is known for having jaw-dropping, colorful patterns and a large nuchal hump that grows on the heads of males. Flower horn fish are especially valued in certain Asian cultures because they are thought to bring good luck and prosperity. Although flowerhorns can be playful and friendly towards their owners, they can be quite aggressive towards other animals within their territory. We suggest keeping one in a 40-gallon aquarium with no other tankmates. When it gets bigger, your wet pet will eat lots of food and therefore need more water changes to keep the water clean. After many years of enjoyment with the 40-gallon fish tank, we recommend upgrading to a 55 or 75 gallon aquarium for your growing pet.

2. The Community Aquarium

Bolivian rams, julii corys, and black skirt phantoms

If one showpiece fish per tank is not your idea of fun, let’s go the opposite direction and fill the 40-gallon tank with many different species. First, we want to get one to three pairs of Bolivian rams (Mikrogeophagus altispinosus). They are known for their beautiful, trailing fins and will serve as the 3-inch (7.6 cm) centerpiece fish for this community tank. Make sure you have plenty of decorations and aquarium plants to obscure line of sight to avoid territorial disputes. Then add a school of julii corydoras that will help clean the fish tank by constantly scavenging for leftover food stuck in the substrate. Since you have a medium-sized aquarium to work with, choose a stockier, midlevel schooling fish. Black phantom tetras are a favorite of ours (Hyphessobrycon gigalopterus) due to their strikingly high dorsal feathers.

All of these fish are pretty hardy, live in similar water parameters, and are safe with aquatic plants. These fish eat omnivore food, including frozen bloodworms, pellets and Repashy gel foods. This is the foundation of your 40-gallon community tanks. Feel free to spice it up with some of your personal favorites – like a rare pleco, snails, rainbow shark, or some oddball fish.

3. The “Breeding for Profit” Tank

Female albino long fin bristlenose pleco

With a 40-gallon breeder aquarium, there are of course many species that you can try spawning, such as long fin bristlenose plecos. This catfish runs between 4-5 inches (10-13 cm) long but has giant finnage that takes up more space than normal bristlenose plecos. To accommodate their larger wingspan, they require larger caves. You can breed them in a smaller aquarium, but once they start producing lots of fry, you will have to regularly move the offspring to other fish tanks.

To prevent babies being accidentally sucked up, we use soft sponge filters. Then we condition the adults for breeding by feeding plenty of their favorite foods, like Repashy gel food, sinking wafers, bloodworms, and blanched zucchini. The fry are smaller and prefer to eat live baby brine shrimps, driftwood, crushed flakes, canned green beans, and algae.

The long-fin bristlenose plecos are available in many different varieties, such as the super red, green dragon, and chocolate. Start a relationship with your local fish store and find out which types have the highest demand so that you can sell your juvenile plecos to them. For more information, see our article on breeding fish for profit.

4. The African Cichlid Tank

Male and female saulosi cichlids

Most African cichlids require larger fish tanks, but the saulosi cichlid (Chindango saulosi or Pseudotropheus saulosi) is a dwarf mbuna from Lake Malawi that only grows up to 3.5 inches (9 cm). The sexual dimorphism of males and women makes them appear like two distinct species. This is why they are visually amazing. The dominant male is a bright blue with dark vertical stripes. While the females are solid sunshine yellow. Subdominant males can range from yellow to lightblue with slight barring.

For a 40-gallon tank, we recommend 1-2 males with 4-5 females. They require high pH, high GH and KH as well as a high diet rich in vegetation and roughage. They also need lots of rocks and hiding spaces to minimize territorial disputes. Saulosi Cichlids are easy to breed. Females may hold eggs in their mouths until the fry start swimming free. The fry can be placed in a separate grow-out aquarium or left to hide in the rockwork while they mature. You should try the dwarf mbuna if you want an aquarium that is as fun and colorful as saltwater tanks.

5. The Rare Fish Colony

Trout goodeid

We chose the trout goodeid, Ilyodon furcidens, as our final stocking choice. This rarer species of Central American livebearer looks almost like a miniature 3.5-inch (9cm) trout. Like most livebearers, they prefer higher pH and GH, but they are a bit unusual because they require temperatures cooler than 72degF (22degC). Thankfully, they are not picky eaters and eagerly eat flakes, pellets, and even hair algae in your planted aquarium. You could mix them with other fish, but we like experiencing them as a single-species colony to see the unique behaviors that come out when they’re only surrounded by their own kind. Another good usage for a 40-gallon breeder aquarium would be conservation of endangered fish species. If you are interested helping to preserve at-risk fish, search online for the “CARES Preservation Program” to find out more.

These profiles for 40-gallon aquariums should be inspiring to you. You can also find many stocking ideas for 10-gallon or 20-gallon tanks. While Aquarium Co-Op does not ship fish, you can see our list of preferred online vendors that sell aquarium animals. All the best and have a wonderful time in nature!