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When planning out what kind of fish to add to an aquarium, we like to pick species that live in different layers of the water column. Instead of having animals that cluster in the same area, the entire tank is filled with interesting activity. Since we’ve already talked about our favorite top-dwelling fish and bottom dwellers, let’s show off the most colorful and lively options that swim in the middle of the aquarium. 

1. Green Neon Tetra

Paracheirodon simulans

The green neon tetra is the smaller cousin of the regular neon tetra and has an iridescent blue-green horizontal stripe that shines brightly even when the aquarium light is turned off. They only grow to 1 inch (2.5 cm) long, so a school of six green neons can live in a nano tank as small as 5 gallons. Because of their small size, they feel most comfortable in larger groups with lots of aquarium plants and other cover. Plus, they require tiny foods that can fit in their mouths, such as frozen cyclops, Easy Fry and Small Fish Food, crumbled flake food, and baby brine shrimp.

2. Pygmy Corydoras

Corydoras pygmaeus

Cory catfish are widely considered to be bottom dwellers, but some species like the pygmy cory display unusual behaviors. This 1-inch dwarf corydoras is known for fluttering its fins and hovering like a hummingbird in the middle of the tank. They also like to perch on plant leaves and driftwood that are above the ground. Their whisker-like barbels help them to find foods such as sinking wafers and Repashy gel food. To breed them in a colony, consider putting the pygmy corys in a mature, species-only tank with plenty of mulm, biofilm, and plants for the fry to graze off.

3. Serpae Tetra

Hyphessobrycon eques

Smaller species can sometimes be a little on the shy side, so if you’re looking for a fish with bright colors and a confident personality, try the serpae tetra. Their red-orange bodies with black and white markings provide a pop of color, especially in planted aquariums. Serpae tetras can grow up to 2 inches (5 cm) in size and aren’t afraid to boldly swim out in the open. Because of their rowdy behavior and potential for fin nipping, we recommend getting at least 8–10 in a school and keeping them with other fast-swimming fish, like black skirt tetras and zebra danios.

4. Dwarf Neon Rainbowfish

Melanotaenia praecox

Technically, most rainbowfish like to hang out in the upper half of the water column, but we wanted to sneak in this beautiful, almond-shaped fish because of its shimmery blue scales and red-orange fins. These speedy swimmers can grow up to 3 inches (8 cm) in size and get along with most similar-sized fish with peaceful to semi-aggressive temperaments. Feed them a healthy mix of bloodworms, brine shrimp, flakes, and live fish foods to get the brightest colors and healthy growth out of them. Read our full care guide to learn more.

5. Von Rio Tetra

Hyphessobrycon flammeus

Also known as the flame tetra, this species has a striking appearance with a yellow front half and red back half. Their length ranges from 1.5–2 inches (4–5 cm) with a deep-bodied profile. Their calm nature and small size make them the ideal residents for a planted community tank. You may see some minor chasing amongst themselves, but this is typical tetra behavior in which the males show off to the females and establish their social hierarchy.

6. Harlequin and Lambchop Rasboras

Trigonostigma heteromorpha and Trigonostigma espei

Both of these peaceful rasboras are well-loved staples in the world of community tanks. Their orange bodies and black triangle patches near the tail looks amazing in a forest of underwater plants. Harlequin rasboras can reach up to 2 inches (5 cm), while lambchop rasboras stay slightly smaller around 1.5 inches (4 cm). Because of their hardiness and ability to live in a wide range of parameters, they do well with beginners and are commonly available in most pet stores. Read about their care requirements for more info.

7. Congo Tetra

Phenacogrammus interruptus

Another bigger schooling fish on our list that does well in medium to large aquariums is the 3-inch (8 cm) congo tetra. Males are known for their shiny blue and red-orange horizontal stripes and flowy finnage, whereas females are smaller in size and have a silvery-gold sheen. As long as their tank mates are not fin nippers, these tetras can live with most community fish like rainbowfish, livebearers, and unaggressive catfish.

8. Celestial Pearl Danio

Danio margaritatus

One of the darlings of the aquascaping world is the celestial pearl danio (CPD) or galaxy rasbora. Their bright red-orange fins and golden-dotted bodies make them look like tiny brook trout, which is perfect for building a nature scape. They can be a little timid, but we’ve had good luck in coaxing them out by increasing their school size, providing lots of aquarium plants as shelter, and ensuring none of the tank mates are bullying them. Also, they prefer cooler waters from 72–76°F (22–24°C) and can potentially live without an aquarium heater, depending on your room temperature. For more details, see their full care sheet.

9. Cherry Barb

Puntius titteya

Cherry barbs are often overlooked because barbs have a bad reputation for being boisterous fin nippers, but this species is an excellent tank mate for peaceful community aquariums. Males display an intense red while females are more tannish-red, and both have a black horizontal stripe running down their sides. Not only are they as friendly as similar-sized tetras and rasboras, but they also spawn fairly easily. To help the babies to survive, add lots of dense foliage with a marble substrate and remove the parents soon after breeding.

10. Rainbow Shiner

Notropis chrosomus

If you cannot decide which color would best fit your aquarium, why not try this multicolored minnow from the Southeastern United States? Depending on the breeding condition of the fish, they can display orange, purple, hot pink, blue, black, and more. Rainbow shiners prefer cooler temperatures below 72°F (22°C), so this is the perfect species if you’re looking to make a coldwater aquarium or outdoor mini pond. They do have a shorter life span of around 2–3 years, so check out our forum for tips and tricks on how to successfully breed them at home.

There are so many awesome midwater-dwelling fish that we couldn’t cover them all, so make sure to browse the current stock of our preferred online fish retailers to see everything they have available.