Top 5 Oddball Fish for A 20-Gallon Aquarium


Top 5 Oddball Fish for a 20-Gallon Aquarium

Looking for a fish that is bizarre in appearance, has unique behaviors, or is rarer in availability? These fish are a special category in the aquarium hobby. Some species are hardy and simple to keep, others require special care to adapt to their unique physiology. Learn about 5 of the coolest oddballs that you can keep in a 20-gallon aquarium.

1. Marbled Hachetfish

Carnegiella strigata

This 1.25-inch (3 cm) species is one of the smallest hatchetfish and has a prominent chest that looks like a hatchet blade. The body of this pearly-white hatchetfish is covered with beautiful, dark marbling. The pectoral fins extend out like tiny wings. They are native to the Amazon basin in South America. The area is subject to flooding each year, and the water they come from is black, tannin-rich waters.

The hatchetfish is a top-dwelling fish, capable of leaping out of water to escape predators. Keep your aquarium closed tightly and cover any gaps with craft mesh. If you want them to feel more comfortable, put floating plants like water-sprite in their aquarium. You should also get at least six marled hatchetfish in your school. This species is a good match for other peaceful community fish, which swim in the bottom and middle layers of an aquarium. Small mouths make it difficult to feed these fish small floating foods like Easy Fry and Small Fish Feed, crushed flakes and baby brine shrimps and daphnia. See our hatchetfish care manual for more information.


2. Stiphodon Goby

Stiphodon ornatus

Stiphodon genus is a group of freshwater gobies that hail from Asia and Oceania. They have a slim, eel-like body, similar to kuhli loaches, but about half their length at 2 inches (5 cm). They are also aufwuchs grazers like otocinclus catsfish. This means that they eat algae, zooplankton and biofilm on surfaces all the time. Repashy Soilent Green and frozen daphnia are their favourite foods. While Stiphodon gobies are excellent community fish, the males can sometimes be a bit feisty towards one other, so provide plenty of hiding spots and consider getting more girls than boys, even though the females are less colorful.

3. Peacock Gudgeon

Tateurndina ocellicauda

The peacock gudgeon gets its common name from its amazing array of rainbow colors. Imagine a pink, 2.5-inch (6cm) body with yellow speckling, red vertical stripes and yellow-rimmed fins. There is also a black spot at its base. As you can see in the above picture, males have a distinctive nuchal hump in their forehands. Females have a more straight forehead similar to a tetra or danoio. They come from Papua New Guinea and tend to dwell in the lower half of the aquarium. However, they don’t have a preference for particular foods and will happily eat all floating and sinking community food items you provide. They are generally mild-mannered, but males can be territorial during breeding season. They are quite easy to spawn if you have both sexes and provide 1-inch (2.5 cm) PVC pipes for them to lay their eggs.

4. Blind Cave Tetra

Astyanax mexicanus

The species is actually found in two versions in nature. There’s a (1) normal version that can be found in rivers or lakes, which looks like an ordinary, silvery Tetra, and (2) blind cave versions found underground and in caverns in Mexico. The latter type is more popular in the aquarium hobby because of its shiny, pinkish body and undeveloped eyes covered by skin. They can still find food due to their improved senses of taste and smell. They also have the ability to navigate using their lateral lines, which detect changes in water pressure. The schooling fish can grow to approximately 3-3.5 inches (8-9cm) in length and can be kept in cool water without a heater. Although they are considered a good community fish, they can be aggressive and will nip at anything to explore their surroundings. Keep them away from slower-moving fish or those with long fins. Offer a variety of community foods like flakes, pellets, gel food, and frozen foods to keep them happy and well-fed.

5. Top Hat Blenny

Omobranchus fasciolatoceps

Blennies predominently come from saltwater habitats, which is a shame for freshwater hobbyists because they have such fun personalities and interesting behaviors. Some species can survive in brackish water. This includes the top hat Blenny, which is a southern Japanese and Chinese species. While they are often called a freshwater blenny by some, their preference is for brackish water that has a higher pH and GH. As per their common name, males have a rounded crest atop their head, and their entire head and face has a striking pattern of vertical, yellow striping. The rest of their 2.5 to 3 inch (6-8 cm) long, elongated bodies is brown or grayish in color and ends with a yellow tail. They are generally peaceful fish. However, males can be territorial so make sure to provide rocks and caves for them shelter. They love brine shrimps, baby brine shrimps, dried seaweed, spirulina flakes, and algae that you scrape from the tank sides.

If you love the idea of oddball fish but only have the room to set up a 10-gallon aquarium, then don’t forget to check out our previous article that covers some of our favorite nano-sized picks.