Fish care

Best fish for beginners: hardy picks by tank size

By The FishFits team · Updated

The best fish for beginners are small, peaceful, captive-bred species that cope with a range of water: guppies, platies, zebra danios, cherry barbs, harlequin rasboras, neon tetras, bronze corydoras and a single betta or honey gourami. Match them to your tank: a betta in 5 gallons, ember tetras or male endler's livebearers in 10, schools of 8 neons or harlequins in 15–20, and larger mixed communities from 29 gallons. Skip common plecos, oscars, clown loaches and goldfish in small tanks, because they outgrow beginner aquariums.

A good first fish forgives the small mistakes every new fishkeeper makes. It stays small, gets along with other fish, eats ordinary flakes and copes with the water that comes out of your tap. The picks below are sorted by the tank they actually need, using the minimum tank and group sizes from our species data, the same numbers our stocking calculator uses.

What makes a fish good for beginners

A fish is beginner-friendly when most of these are true:

  • It stays small enough for your tank as an adult. Most good picks for tanks of 20 gallons (76 L) or less stay under about 3 in (7.5 cm).
  • It is peaceful. No territory fights and no fin nipping.
  • It tolerates a range of water. Farm-bred fish that handle normal tap water, so you don’t need to chase pH with chemicals.
  • It eats prepared food. Flakes, micro pellets or sinking wafers, not live food only.
  • It is bred in captivity and sold everywhere. Healthy, well-fed stock is easy to find.
  • Its group fits your tank. A schooling fish that needs 8 friends is only easy if you have room for 8.

Every fish recommended below is rated “easy” in our species data unless the text says otherwise.

Best beginner fish at a glance

Fish Adult size Minimum tank Minimum group Temperature
Betta (male) 2.6 in (6.5 cm) 5 gal (19 L) 1 75–82 °F (24–28 °C)
Honey gourami 2 in (5 cm) 10 gal (38 L) 1 73–81 °F (23–27 °C)
Ember tetra 0.8 in (2 cm) 10 gal (38 L) 8 73–82 °F (23–28 °C)
Endler’s livebearer 1.2 in (3 cm) 10 gal (38 L) 3 75–82 °F (24–28 °C)
Guppy 2 in (5 cm) 10 gal (38 L) 3 72–81 °F (22–27 °C)
Neon tetra 1.4 in (3.5 cm) 15 gal (57 L) 8 70–77 °F (21–25 °C)
Harlequin rasbora 1.8 in (4.5 cm) 15 gal (57 L) 8 72–81 °F (22–27 °C)
Cherry barb 2 in (5 cm) 15 gal (57 L) 6 73–81 °F (23–27 °C)
X-ray tetra 1.8 in (4.5 cm) 15 gal (57 L) 6 75–82 °F (24–28 °C)
Platy 2.4 in (6 cm) 15 gal (57 L) 3 68–79 °F (20–26 °C)
White cloud mountain minnow 1.6 in (4 cm) 15 gal (57 L) 6 61–72 °F (16–22 °C)
Zebra danio 2 in (5 cm) 20 gal long (76 L) 6 64–77 °F (18–25 °C)
Bronze corydoras 2.8 in (7 cm) 20 gal long (76 L) 6 70–79 °F (21–26 °C)
Kuhli loach 3.5 in (9 cm) 20 gal (76 L) 6 75–81 °F (24–27 °C)
Bristlenose pleco 4.7 in (12 cm) 20 gal (76 L) 1 72–79 °F (22–26 °C)
Pearl gourami 4.5 in (11.5 cm) 29 gal+ (110 L), at least 35 in (90 cm) long 1 75–82 °F (24–28 °C)
Swordtail 4.7 in (12 cm) 29 gal+ (110 L), at least 35 in (90 cm) long 4 72–79 °F (22–26 °C)
Rosy barb 3.5 in (9 cm) 29 gal+ (110 L), at least 35 in (90 cm) long 6 64–75 °F (18–24 °C)

Livebearers (guppies, endlers, platies, swordtails) prefer hard, alkaline water around pH 7–8. Tetras and rasboras are happier in soft to neutral water, though farm-bred fish adapt to most tap water. Test yours before you shop and pick fish that suit it.

Best fish for 5 and 10 gallon tanks

Small tanks heat up, cool down and build up ammonia faster than big ones, so stock them lightly and keep the list short.

5 gallons (19 L): one male betta is the only fish we’d put in a tank this size. Give it a heater set to about 78–80 °F (26–27 °C) and a gentle sponge filter, because long fins tire in strong current. A 5 gallon is also a fine size for a snail or a small dwarf shrimp colony, but not alongside a betta, which often hunts shrimp.

10 gallons (38 L): pick one of these, not all of them.

Plan Stock Shared temperature Notes
Nano school 8–10 ember tetras 73–82 °F (23–28 °C) Best in a planted tank with soft to neutral water
Livebearer group 6 male endler’s livebearers 75–82 °F (24–28 °C) Males only means no babies. Use a tight lid
Guppy trio 3 male guppies 72–81 °F (22–27 °C) Males only. A female can give birth every 4–6 weeks
Gourami and school 1 honey gourami + 8 ember tetras 73–81 °F (23–27 °C) One of the calmest centerpiece fish for a 10
Betta tank 1 betta, plus snails 75–82 °F (24–28 °C) Some bettas accept tank mates at 10 gal and some attack them; see betta tank mates

Pygmy corydoras also fit 10 gallons, but our data rates them “moderate” and they need a group of 10. Treat them as a second step once the tank is stable. If you are still choosing a tank, a 20 gallon long is barely more work than a 10 and is far more forgiving.

Best fish for 15 and 20 gallon tanks

This is the best size range for a first community tank. It is big enough to stay stable, and a weekly water change is still a small job.

Tank shape matters. A 20 gallon long (30 × 12 in) gives active fish 6 in (15 cm) more swimming length than a 20 high (24 × 12 in). Zebra danios and bronze corydoras both need a tank at least 30 in (75 cm) long in our data, so they belong in the long version.

We ran every stock list on this page through our stocking calculator at adult size, using each tank’s real length, and none of them triggered a warning. The 20 and 29 gallon lists use roughly 50–80% of the calculator’s waste and space limits, so build up to them in stages rather than buying everything at once:

Tank Stock Shared temperature
15 gal (57 L) 8 neon tetras + 8 ember tetras 73–77 °F (23–25 °C)
20 gal (76 L) 10 neon tetras + 6 peppered corydoras 70–77 °F (21–25 °C)
20 gal (76 L) 8 cherry barbs + 8 harlequin rasboras 73–81 °F (23–27 °C)
20 gal (76 L) 1 bristlenose pleco + 10 neon tetras 72–77 °F (22–25 °C)
20 gal long (76 L) 4 platies + 6 bronze corydoras 70–79 °F (21–26 °C)
20 gal long, unheated 10 white cloud mountain minnows + 6 zebra danios 64–72 °F (18–22 °C)

A few tips for this size:

  • Platies: keep more females than males, or all males, so the males don’t wear the females out. Expect fry from any mixed group.
  • Neon tetras: add them after a hardier group has settled in. They do best in a mature, stable tank, not a brand-new one.
  • Zebra danios: keep 6 or more. In smaller groups they can nip slow, long-finned fish, so don’t mix them with bettas or fancy guppies.
  • Corydoras: use sand or smooth gravel and feed sinking food, so the bottom group gets its share.
  • No heater? White clouds and zebra danios are the best choice for a room that stays around 64–72 °F (18–22 °C). Most other fish on this page need a heater.

Best fish for 29 gallons and up

From 29 gallons (110 L) you can mix three kinds of fish, such as a centerpiece fish, a larger school and a bottom group. A bristlenose pleco fits well here too. It stays about 4.7 in (12 cm) and grazes algae and wood, but algae alone won’t feed it, so add sinking wafers and blanched vegetables after the lights go out.

Tank Stock Shared temperature
29 gal (110 L) 6 zebra danios + 5 platies + 6 bronze corydoras 70–77 °F (21–25 °C)
29 gal (110 L) 1 bristlenose pleco + 8 cherry barbs + 8 X-ray tetras 75–79 °F (24–26 °C)
29 gal (110 L) 1 honey gourami + 10 harlequin rasboras + 6 bronze corydoras 73–79 °F (23–26 °C)
40 gal breeder (151 L) 1 pearl gourami + 10 harlequin rasboras + 6 kuhli loaches 75–81 °F (24–27 °C)

Pearl and honey gouramis are among the calmest gouramis you can buy. The pearl gourami has long fins and feelers, so keep it away from fin nippers. Males are territorial with each other, so keep one male, with two or three females if you want more than one.

Kuhli loaches need soft sand and hide by day, so plant the tank well, look for them at feeding time and cover the filter intake with a sponge so they can’t slip inside. They also react badly to some medications, so read the label before treating a tank that holds them.

A standard 29 gallon is only 30 in (76 cm) long. Pearl gouramis, swordtails and rosy barbs need about 35 in (90 cm) of swimming length in our data, so in practice they suit a 40 gallon breeder (36 in, 91 cm) or a 55 gallon (48 in, 122 cm). Rosy barbs also like cooler water, 64–75 °F (18–24 °C). Giant danios are easy too, but they need a 55 gallon (208 L) tank 4 ft (120 cm) long.

These are often sold to beginners. They aren’t bad fish, but each one has a catch:

  • Tiger barbs, serpae tetras and Buenos Aires tetras: hardy, but notorious fin nippers. Tiger barbs need a group of 8 in 29 gallons (110 L). Never keep them with bettas, gouramis, angelfish or fancy guppies.
  • Mollies: rated “moderate” in our data. They need 29 gallons (110 L), warm water and hard, alkaline water around pH 7.5–8.5.
  • Dwarf gouramis: rated “moderate”. Mass-bred stock can carry dwarf gourami iridovirus, which is very infectious, can pass to other fish and has no known cure, and males fight each other. A honey or pearl gourami is the easier choice.
  • Otocinclus: rated “moderate”. They need a group of 6 in a mature tank of 20 gallons (76 L) with algae to graze, and can starve in a new, clean tank.

Fish beginners should avoid

Most fish on this list are sold as juveniles of about 2–3 in (5–8 cm). The tag rarely says how big they get, and few are easy to rehome once they outgrow the tank.

Fish Adult size What it really needs Try instead
Common pleco 16 in (40 cm) or more 150 gal (568 L), 6 ft (180 cm) long. Produces a lot of waste Bristlenose pleco: 4.7 in (12 cm), 20 gal (76 L)
Oscar About 12 in (30 cm), sometimes 14 in (35 cm) At least 75 gal (284 L) and 4 ft (120 cm) long for one adult, and Seriously Fish advises about 140 gal (540 L). Eats any fish that fits in its mouth Pearl gourami as a centerpiece
Goldfish in a small tank or bowl Commons 10–12 in (25–30 cm) or more At least 75 gal (284 L) for one common goldfish, or a pond. Fancies need at least 20 gal (76 L) plus 10 gal (38 L) per extra fish. Coldwater fish with heavy waste White clouds for an unheated tank
Iridescent shark 3 ft (90 cm) or more A tank far larger than a typical home aquarium. Turns skittish in cramped tanks and injures itself on the glass Zebra danios for open-water action
Clown loach 10 in (25 cm) or more A group of 5 or more in at least 180 gal (681 L), 6 ft (180 cm) long Kuhli loaches: group of 6 in 20 gal (76 L)
Bala shark, tinfoil barb 12 in (30 cm) or more A school of 5–6 in at least 200 gal (757 L) Cherry barbs or harlequin rasboras
Chinese algae eater 8–11 in (20–28 cm) One fish in 80 gal (304 L). Turns territorial with age Bristlenose pleco
Red-tail and rainbow sharks 4.7–6 in (12–15 cm) One per tank, at least 55 gal (208 L), 4 ft (120 cm) long. Adults chase bottom dwellers Wait until your second tank

Sailfin catfish, which are often sold as common plecos, now live in the wild in Florida, Texas, Hawaii and several Southeast Asian countries. Most of those populations started from released aquarium fish, and some from fish farm escapes. Never release aquarium fish into the wild. Ask your local fish store or club to take fish you can’t keep.

How to stock your first tank, step by step

  1. Cycle the tank first. Grow the bacteria that remove ammonia before any fish go in. Our fishless cycle guide shows how, and it usually takes 4–8 weeks.
  2. Test your tap water. Note the pH and hardness, then shortlist fish that suit it, such as livebearers for hard water or tetras and rasboras for soft water.
  3. Pick a simple layout. One schooling fish for the middle, one bottom group and, at most, one centerpiece fish.
  4. Check every pair. Add your species to the compatibility checker, then check the whole stock in the stocking calculator.
  5. Buy the hardiest group first. Platies, zebra danios or cherry barbs are good starters. Choose a shop with clean tanks, and skip any tank that has dead or sick-looking fish in it. If you have room for a spare tank, keep new fish apart for a few weeks first, because it is the safest way to stop disease reaching your main tank.
  6. Wait and test. Test ammonia and nitrite every few days for 2–3 weeks. Add the next group only when both stay at 0 ppm.
  7. Add the centerpiece last. A betta or gourami added last is less likely to claim the whole tank.
  8. Acclimate every new group. Float the bag and mix in tank water slowly, as in our acclimation guide.

Common beginner mistakes

  • Buying the tank and the fish on the same day. New tanks have no bacteria, and ammonia climbs within days.
  • Buying 2 or 3 of a schooling fish. Neons and harlequins need 8 in our data. Small groups hide, lose color and stay stressed.
  • Trusting the inch-per-gallon rule. It ignores adult size, body bulk and tank length. Our guide on how many fish per gallon explains a better method.
  • Buying an “algae eater” without checking its adult size. Common plecos and Chinese algae eaters are the classic traps.
  • Mixing goldfish with tropical fish. Goldfish want cooler water and produce much more waste.
  • Mixing fin nippers with long fins. Tiger barbs and bettas are a bad pair.
  • Keeping male and female livebearers without a plan. Guppy, endler and platy females can give birth every 4–6 weeks and can store sperm for later broods, so a female from a mixed shop tank may already be pregnant. Keep males only, or have a plan for the fry.
  • Overfeeding. Feed small amounts once or twice a day. Uneaten food rots and raises ammonia.
  • Guessing when a fish looks sick. If a new fish hides, clamps its fins or stops eating, test ammonia and nitrite first, because poor water is a common cause in new tanks. If you use a medicine, follow the label exactly, and ask an aquatic vet if fish keep getting sick or dying.

Gear mentioned in this guide

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Frequently asked questions

What is the hardiest fish for a beginner?

Zebra danios, platies, white cloud mountain minnows and bronze corydoras are among the toughest. They handle a fairly wide temperature range and forgive small mistakes. Even hardy fish suffer in an uncycled tank, though, so cycle the tank first and add fish one group at a time.

How many fish can I put in a 10 gallon tank as a beginner?

Plan on one small school, such as 8–10 ember tetras or 6 male endler's livebearers, or a single betta or honey gourami as the centerpiece. Neon tetras, platies and most corydoras need 15–20 gallons (57–76 L) or more.

Are goldfish good fish for beginners?

Only if you have a pond or a very large tank. Common goldfish reach 10–12 in (25–30 cm) or more and need at least 75 gallons (284 L) for one fish in our data, while fancy goldfish need at least 20 gallons (76 L) for the first fish plus 10 gallons (38 L) for each extra one. They are coldwater fish, so don't mix them with tropical species.

Is a betta a good first fish?

Yes, if it gets a heater, a gentle filter and at least 5 gallons (19 L), with 10 gallons (38 L) being easier to keep stable. Keep only one male per tank, skip fin-nipping tank mates such as tiger barbs, and be ready to keep it alone, because some bettas attack every tank mate.

Which fish should I add first to a new tank?

Once the tank is cycled, start with a hardy group such as platies, zebra danios or cherry barbs. Add bottom dwellers and more delicate fish a few weeks later, and add a centerpiece fish such as a betta or gourami last.

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