Harlequin Rasboras are a great beginner fish for a small aquariumHarlequin Rasboras (Trigonostigma heteromorpha)

Being new to any hobby can be overwhelming, and the aquarium hobby is no exception. One of the biggest questions almost everybody new to the hobby has is what are some of the best beginner fish for my aquarium. A quick Google search can come up with more results than any one person can read (approximately 525,000 as of this writing), but most of them will suggest more or less the same fish. Fish like livebearers (mollies, guppies, swordtails), dwarf gourami, barbs, and tetras are justifiably recommended, but there are also other fish that don’t get as much attention. So we decided to highlight some less common fish that beginners could easily have success with.

The first question when choosing any fish should always be what size tank you are trying to stock. We recommend the largest tank your space and budget allows, a 55 or 75 gallon aquarium would be arguably the best size aquarium for a beginner, but we know that most beginners choose to go smaller. This list is largely based off of a very common scenario: a new fishkeeper who is starting up a small tank (20 gallons or less) and who wants a community of fish that can live together. Also, when choosing what tank to buy, make sure you are prepared to confront the challenges that small tanks create and avoid many of the most common mistakes new aquarium keepers make. 

When choosing what fish to keep, one of the best ways to plan is by looking at different niches that can be filled and choosing fish to fit those roles. 

Mid-Level Swimmers

Looking at where fish prefer to stay can help you create a tank that has activity spread throughout. While small tanks are naturally limited on space and tend to force fish closer together, this is still a good place to start. Mid-level fish are the ones most people are going to think of and look at. They swim more or less everywhere in the tank, but generally hang out more in the middle half of the vertical space. Because this is such a common place for fish to live, you have a lot of choices.


  • Furcata RainbowPseudomugil furcatus – When most aquarists think of rainbowfish, they tend to think of the larger species such as Boesemanis, Madagascars, and Turquoise Rainbows, and these are all great fish to keep. But, for those with smaller tanks, they all get too large. However, the Blue Eyed Rainbows of the Pseudomugil genus are an exception. Furcata Rainbows are generally readily available, hardy, and peaceful community fish. With blue eyes, yellow fins, and occasionally red cheeks (when the males are trying to show off), they offer a nice splash of color into your tank. Like all rainbows, they are a shoaling fish, so try to keep at least a small group of them.
  • Threadfin RainbowIriatherina werneri – There’s a second rainbow on this list because they’re such an underrated fish that they deserve to get extra attention. Like the Pseudomugil rainbows, Threadfins are small enough to make great additions to small aquariums. With silver bodies and long, narrow red, yellow, and black fins,  Threadfin Rainbows offer a graceful touch to your aquarium. Keep them in groups and they’ll show the most colors as males compete for attention.
  • Harlequin RasboraTrigonostigma heteromorpha – While more common than many others on this list, Harlequin Rasboras make great schooling fish. The standard fish has a nice golden red and black body, but you can also find them with more purple and black shades. They rarely exceed an inch, which means you can add a nice school to even a fairly small tank. 
  • Peacock GudgeonTateurndina ocellicauda – Somewhat less common than the others mentioned, Peacock Gudgeons are an extremely underrated yet beautiful fish. With a bluish-purple body, red stripes, and yellow trim around the fins, they offer a great and compact mix of colors in a fish that rarely reaches three inches. While they can be somewhat territorial with each other, they show almost no aggression towards different species, so work great as individuals with other fish.

Surface Swimmers

While most fish are going to stay in the middle, there are a handful that prefer to swim at the top. Perhaps most notably of these is the Silver Hatchet (Thorachocharax stellatus). They rarely get larger than an inch and a half and do well when kept in small numbers or large groups. The one thing to keep in mind is that most fish who live at the surface have evolved to escape danger by jumping from the water, so make sure to keep a well fitting lid on your tank to avoid startled fish landing on the floor.

Bottom Dwellers

With activity at the top and in the middle, it is often good to look at adding fish who like to stay near the bottom. My favorite bottom fish are the Cory Cats (Corydoras spp). Almost all Cories are schooling fish, which means many of the larger species are not going to be a great choice for small tanks. There are several dwarf and pygmy Cory Cats, but they can be a little delicate and unforgiving of lapses in water quality. But there are also a number that fit into the Goldilocks zone of being just right. Panda Cories (Corydoras panda) stays at a very manageable two inches or less, is very hardy, and has an attractive black and white pattern that makes them a great choice.

Algae Eaters

One of the biggest questions is always what are the best choices for an algae eater in an aquarium. The ubiquitous solution is the Common Plecostomus, but due to their size (up to 24 inches or more) they are unsuitable for small aquariums. However, there are several good choices for algae control. Keep in mind, though, that just because they eat algae doesn’t mean they keep your water clean, so you will have to continue regular tank cleanings just as often (or more so) as you would without them.

  • White Seam Bristlenose PlecoAncistrus dolchopterus ‘l183’ - Among the Plecos, not all of them do equally well eating algae. Some are more carnivorous and scavengers while others more chew on driftwood. However, the White Seam Bristlenose does do a good job of chewing on algae while not growing to unmanageable sizes. This four inch pleco also sports attractive white spots and a white edge to its fins that makes for an attractive fish, when it’s not hiding.
  • Nerite SnailClithon diadema – So this isn’t a fish, but it’s one of the best choices for algae control. Freshwater Nerite Snails are voracious algae eaters who don’t add much to an aquarium’s bioload. They have attractive shell shapes and patterns and, unlike many freshwater snails, only reproduce in saltwater, making it impossible for them to overtake your aquarium.


Cichlids are appealing to many fish keepers because of their robustness and attitude. Unfortunately, most are simply too large for any small aquarium. But there are some small species that can make for great choices for a beginner with a small tank.

  • Brichardi CichlidNeolamprologus brichardi – While very small tanks aren’t suitable for Brichardi Cichlids, a small group could easily be kept in a 20 gallon. They are perhaps the fish on this list that requires the most thought when setting up, but they are still easily kept by beginners. They prefer harder, more alkaline water, though they have been known to breed in neutral conditions. They also should be provided plenty of rocky, cave-like decorations to claim as territories. They are highly territorial towards other fish, so keep them as a species only tank when keeping them in a small aquarium.
  • Kribensis Pelvicachromis pulcher – Another small cichlid, Kribensis are very forgiving of water conditions and make for a great beginner cichlid. Like Brichardi, they can be fairly territorial, especially when breeding, and probably will do best if kept as a single species setup. A trio would fit well in a 20 gallon aquarium, and you might be able to keep a stout fish that doesn’t compete for space such as a White Seam Bristlenose Pleco.


If we’re going to look at unusual choices that aren’t generally listed by other people, there are definitely some oddballs that don’t easily fit into a category with other choices.

  • Dwarf BB PufferCarinotetraodon travancoricus – Puffers have many fans because of their unusual personalities and appearances, but most of them are unsuitable for beginners with small tanks. Most require a brackish setup and grow relatively large. However, the Freshwater Dwarf BB Puffer is an exception. They live in completely freshwater conditions and stay below one inch in length. They do share the somewhat nippy personalities of their larger cousins, so they’re another fish that do best in a species only setup. Give them a well decorated aquarium (they love densely planted setups) and they will happily explore their surroundings ceaselessly. And they’re small enough that you can keep a sizable group in a 10 gallon aquarium.
  • Neocaridina ShrimpNeocaridina spp – The most famous Neocaridina Shrimp is the Red Cherry Shrimp, but you can find an enormous variety to choose from. Black Carbon, Blueberry, Bumblebee, Orange Rili, there are many colors and patterns to find what you like the best. They do require clean water, so you may need to be more careful about staying on top of water changes, but as long as you do that they are very hardy. All shrimp are seen as food for fish, so if you want to keep them in a community setup, make sure to choose fish that are too small to eat them. A group of shrimp and plants can thrive in even the smallest aquariums.

Putting Them Together

For all but the smallest aquariums, there are an almost endless number of ways you can choose to stock them. Even limiting yourself to the fish listed here will give you a wide variety of setups. But to give you some ideas, we have a few examples of what you could choose.

5 Gallon Shrimp Tank 

  • 25 x Red Cherry Shrimp
  • 1-2 x Horned Nerite Snail
  • Dense Collection of Easy Plants

Tanks 5 gallons and smaller are problematic for a number of reasons and generally shouldn’t be kept by beginners. However, if you want to go that small, setting up a shrimp tank is perhaps the best option you can choose. Shrimp put off a very small amount of biological waste and can be stocked very densely before causing problems. Some people would even say you can easily keep a breeding colony of 50 shrimp in a 5 gallon. Aiming to start with 25 will give you a fair amount of activity and give you room for the colony to grow as they start to breed. Plants always introduce some complexity to an aquarium, but there are easy plants that you can have success with. In addition to consuming excess nutrients in the water, the plants will give an ideal place for the shrimp to live. One or two Horned Nerite Snails should be more than enough to handle any algae problems you may face.

10 Gallon Rainbow Tank 

  • 3 x Panda Cory
  • 3 x Threadfin Rainbow
  • 2 x Silver Hatchet
  • 3 x Horned Nerite Snail

10 gallons are one of the most popular beginner sized tanks. While I’d still recommend going bigger, there are a number of stocking options. In this setup, the three Threadfin Rainbows will be the star of the aquarium while the Panda Cories and Silver Hatchets help bring live and excitement to other parts of the tank. The rainbows and hatchets will be most comfortable when kept with some cover such as tall plants (either live or fake will work well), but leave some open floor space for the cories to swim unencumbered. Three Horned Nerites will help control algae.

20 Gallon Tank

  • 9 x Harlequin Rasbora
  • 5 x Panda Cory
  • 1 x Peacock Gudgeon
  • 1 x White Seam Bristlenose Pleco

With 20 gallons, the options open up a lot. In this layout, you have space to start forming some shoals of fish. The five Panda Cories will likely often stay in a group while the nine Harlequin Rasboras will likely form a looser shoal. The Peacock Gudgeon will mostly stay to himself, but happily explore all parts of your tank. Having a little more space, the White Seam Bristlenose will work on algae control. Giving some cover in the form of decorations or plants will help the gudgeon and rasboras be happiest while it’s always recommended to give the pleco some driftwood.