5 Best Fish Tank Ideas for A 20-Gallon Aquarium


5 Best Fish Tank Ideas for a 20-Gallon Aquarium

It’s like starting from scratch when you buy a 20-gallon new aquarium. There are so many possibilities when it comes to choosing the decorations, live plants, and of course aquarium fish. These are five of the best setup ideas that we love to share with you.

1. The “I Just Want It to Look Good” Aquarium

If you are not an expert aquascaper, or a creative artist, it might be difficult to create an exquisite design for your aquarium. This first setup is simple, but it’s a stunning show-stopper every time you look at it. The aim is to fill the aquarium’s rear half with plants in a variety of textures and colors. To maximize impact, drop in 12-20 neon Tetras. There’s something instantly mesmerizing about seeing a large group of identical fish swimming in an underwater forest of plants.

Neon tetras tend to swim in the middle of the aquarium, so you can add a few bottom dwellers to round out the community, such as a red cherry shrimp colony that pops against the greenery, three to four kuhli loaches to clean up the tank at night, or a few nerite snails for algae control. You can keep your tank clean by choosing slow-growing plants and animals that aren’t likely to breed quickly. Everyone is drawn to this setup because it isn’t jumbled with a dozen different species but rather looks like an carefully crafted work of art. The simplicity of its beauty will get people thinking, “Why don’t I do a tank like this?”

Neon tetras have bright blue and red stripes that really stand out against a wall of aquatic plants.

2. The “Fish Breeding” Aquarium

Setting up a dedicated tank for breeding fish is enjoyment for the whole family. You can teach kids about nature, get your partner more interested in aquariums, and even sell the offspring to your local fish store or other hobbyists for profit. Most people start with livebearers (or fish who bear live young) like guppies or platies, but have you ever considered breeding bristlenose (or bushynose) plecos before? Because they are easy to breed, many varieties have been created, including wild-type brown, albino and super red plecos. You should provide a pleco cave that the male can claim as his territory. Feed the male and female lots of nutritious foods, like frozen bloodworms and Repashy gel foods, to get them ready for spawning. Then the male will entice the female to his cave, trap her inside to lay eggs, and faithfully fan the eggs (to increase water flow) until they hatch. You can also keep the parents in a larger aquarium. Once the eggs hatch, transfer the whole pleco cave with the babies into your 20-gallon tank.

After the fry have learned to swim, you can provide them with plenty of food such as Repashy gel food and flake food. You will need to change the water frequently if you want the fish to stay healthy. Live plants can be added to aquariums to reduce the amount of nitrogen waste and improve the aquarium’s appearance. Java fern and anubias attached to driftwood provide cover for the babies, and the wood introduces biofilm and mulm (or organic debris) for them to snack on. Once they are about 2 inches (5 cm) long, you can move a few of your favorites to other aquariums to help with algae control and sell the rest to your local fish store. You are now ready to start your next breeding project with your 20-gallon aquarium.

In order for breeding to occur, you need at least one male and one female. The male bristlenose plecos have a bushy nose, while the females have a more smooth face.

3. The Rainbowfish Aquarium

Most rainbowfish are too big to fit comfortably in a 20-gallon fish tank, but it’s the perfect size for rainbowfish in the Pseudomugil genus and other dwarf rainbowfish that remain under 2-2.5 inches (5-6.3 cm) long. Some of the most popular species include the neon red (P. luminatus), forktail blue-eye or furcata (P. furcatus), spotted blue-eye (P. gertrudae), Celebes (Marosatherina ladigesi), and threadfin rainbowfish (Iriatherina werneri). Males are more colorful and will dance in the presence of females. Get both sexes to your aquarium to witness this unique behavior.

As surface-dwelling fish, rainbowfish inhabit the top one-third of aquariums, so make sure to have a tight-fitting tank lid that prevents them from jumping out. Add lots of floating plants, mosses, and other dense foliage because they’ll happily lay eggs every day (although you probably won’t see any fry unless you remove the eggs). Because of their small mouths, feed them tiny floating or slowly sinking foods, such as baby brine shrimp, daphnia, cyclops, crushed flakes, micro pellets, and Easy Fry and Small Fish Food.

Dwarf rainbowfish can be a tad more expensive at $10 to $15 each, and ideally you want a school of six or more. To fill out the rest of the tank, you can get other community fish like small tetras and rasboras that swim in the middle and corydoras and snails that scavenge at the bottom. (Cherry shrimp may get picked on since rainbowfish are active creatures that love to eat.)

While dwarf rainbowfish can be a little harder to source, keep searching because their gorgeous colors and lively behavior are worth the hunt.

4. The Oddball Aquarium

Most people think of oddballs as rare or interesting fish, but what about keeping an oddball invertebrate? Filter-feeding shrimp, such as the wood or bamboo shrimp (Atyopsis molucensis), and the vampire shrimp (Atya Gabonensis), have large, feathery hands that are designed to catch and eat small particles in the water. You shouldn’t use a canister or hang-on back filter to remove all the crumbs. You can use a sponge filter, or an airstone with plenty of plants to help them climb on. You can then give them powdered foods such as Repashy gel food, Hikari First Bite and other specialty foods that are suitable for filter-feeding shrimp. You should notice food particles in the aquarium’s water when you add the powder.

For a 20-gallon fish tank, you can get one to two bamboo shrimp and one vampire shrimp. The shrimp grow rather large, ranging from 3-6 inches (8-15 cm) each, so you want them to stand out as the centerpieces of the aquarium by pairing them with nano fish like celestial pearl danios, Norman’s lampeye killifish, and chili rasboras. Also, consider adding some snails, amano shrimp, or cherry shrimp to clean up the food particles that fall to the substrate. This weird, invertebrate-centric community tank might be the right choice for you if you are looking for something different.

If your filter-feeding shrimp are scavenging on ground, then they probably don’t get enough food. Increase their daily portion.

5. The Unheated Aquarium

Looking for fish that can live in a 20-gallon tank with no heater? This danio aquarium might be the right choice if your room temperature is at least 62°F (17°C). Danios are a highly active, torpedo-shaped fish that come in many varieties and colors, such as zebra, leopard, long fin, and even Glofish. Get 12 to 15 of them to create a kaleidoscope of colors zooming around the tank and going crazy during feeding times.

Danios can swim in all aquarium layers. However, you can add other species that prefer cooler water, such as five to six salt and pepper corydoras, to grab any food that passes the danios. Some cool-temperature invertebrates that would work as tank mates include amano shrimp, Malaysian trumpet snails, nerite snails, and Japanese trapdoor snails. You should ensure that your snails get adequate minerals and are given calcium-based food. If you want an action-packed, beginner-friendly tank full of hardy fish, you can’t go wrong with an aquarium of danios.

Long fin zebra danios are very popular because of their high energy, beautiful pattern, and low cost.