Freshwater Fish for Aquariums

Choosing freshwater fish for an aquarium has gotten easier in some ways — there’s more information available than ever — and more confusing in others, because most of that information doesn’t tell you what it’s actually like to keep a species long-term. I’ve kept most of the fish on this list at one point or another, and I’ll tell you what actually matters alongside the standard care specs.

Neon Tetra

Neon tetras are one of the most recognizable aquarium fish and for good reason — that iridescent blue-and-red stripe is genuinely striking, especially in a well-planted tank with a dark substrate where the colors pop. They’re peaceful, schooling fish that need to be kept in groups of at least six. A school of 12 or more moving together through a planted tank is one of those things that’s hard to describe but immediately makes sense when you see it.

Care is straightforward: soft, slightly acidic water in the 6.0-7.0 pH range, temperatures around 72-76°F, varied diet of micro pellets and frozen foods like daphnia or baby brine shrimp. Weekly water changes of 25-30% keep them healthy. They’re sensitive to sudden parameter changes but stable once established.

Betta Fish

Bettas have a reputation for being easy, and they are — relative to other fish. But probably should have led with this: male bettas cannot be housed together and will fight aggressively with any fish that looks remotely similar (long fins, bright colors). One male per tank. They can live with peaceful, non-fin-nipping tank mates like corydoras or small tetras in a properly sized tank.

A 5-gallon tank is the listed minimum, but a 10-gallon gives them room to behave naturally and makes water parameters easier to manage. They’re labyrinth fish — they breathe air from the surface — so don’t cover the tank completely. They like warm water, 76-82°F, and do well on a diet of quality betta pellets plus occasional bloodworms or brine shrimp. Their personalities vary more than most fish; some are curious and interactive, others are territorial and reclusive.

Guppies

Guppies are the fish that made me a fish person originally — active, colorful, and genuinely interesting to watch. They’re livebearers, meaning females give birth to live young rather than laying eggs, which means your population will expand if you keep males and females together. The males display impressive finnage and coloration; the females are plainer but larger. They’re hardy, tolerant of a range of water conditions, and peaceful with other community fish of similar size.

The main gotcha with guppies is overpopulation — a small tank can get overwhelmed quickly if you’re not managing the ratio. Either keep all males or all females if you don’t want breeding, or plan for what to do with fry.

Corydoras Catfish

Cory cats are the workhorses of a community tank — social, entertaining, and constantly busy. They scavenge uneaten food from the substrate, which reduces waste and helps keep the tank cleaner. Their armored bodies and comically earnest rooting around on the bottom makes them genuinely fun to watch. Keep them in groups of six or more; a lone cory is a stressed, inactive cory.

They need a sand or smooth substrate — sharp gravel damages the sensitive barbels on their face, and you’ll notice worn barbels on cory cats pretty quickly as a sign something is wrong. They’re peaceful with virtually everything and are one of the best community fish available at any experience level.

Angelfish

Angelfish are one of those species that changes how your tank looks — their tall, triangular silhouette is distinctive and elegant in a way most fish aren’t. They need vertical space, ideally a tank 18 inches tall or more. They’re semi-aggressive and will establish a pecking order within a group, but they work well in a large community tank with fish too big to eat and not aggressive enough to harass them.

They prefer soft, slightly acidic water and a varied diet. Keep them in groups of five or more — a single angelfish is often shy and less active than one in a social group. They take time to establish themselves but become rewarding long-term residents in a properly set-up tank.

Zebra Danio

Zebra danios are the starter fish that actually hold up over time. They’re fast, active, and genuinely fun to watch — constantly moving in that darting, purposeful way that makes a tank feel alive. Hardy across a wide range of water conditions, which makes them appropriate for new setups where parameters may not be perfectly stable yet. Keep them in schools of five or more and give them open swimming space. They’re peaceful and compatible with most community species.

Discus

Discus are beautiful and high-maintenance, in that order. They require warm water — 82-86°F, which is higher than most community fish tolerate — soft, slightly acidic conditions, excellent filtration, and frequent water changes. Their diet needs to include specialized high-protein food like discus-specific pellets and frozen beef heart or bloodworms. They’re social and need to be kept in groups.

The thing is, discus that are kept in good conditions with proper feeding and water quality are unmatched in a freshwater tank. Their colors are extraordinary and their shape is unlike anything else. But I’d hold off on discus until you’ve successfully maintained a community tank for at least a year and are comfortable with water chemistry. They’re a rewarding fish for experienced keepers, not a first aquarium choice.

Oscar Fish

Oscars are large — 12 inches is typical, sometimes larger — intelligent, and have genuine individual personalities. They learn to recognize their owner, respond to feeding time, and some will accept food from your hand. That level of interaction is unusual in a fish and is a big part of their appeal. The tradeoff is they eat a lot, produce a lot of waste, need a large tank (55 gallons minimum, more is better), and will eat anything they can fit in their mouth. Tank mate selection is critical.

They’re carnivorous and do best on a diet of quality cichlid pellets, frozen shrimp, and occasional feeder fish. They’re worth the investment for someone who specifically wants a large, interactive aquarium centerpiece.

Cherry Barb

Cherry barbs are one of the most underrated community fish — peaceful, the males display vivid red coloration especially during breeding, and they don’t cause problems with tank mates. Keep them in groups of at least five and they’ll consistently show their best color. They like planted tanks with both open swimming space and some cover. Diet of flakes, small pellets, and occasional live or frozen foods keeps them healthy and bright.

Plecostomus

Common plecos are sold as algae eaters at every fish store, and they do eat algae when young. The issue is they grow to 12-18 inches in captivity and eventually need a large tank. If you want an algae-eating pleco that stays a manageable size, look at bristlenose plecos (4-5 inches) or rubber lip plecos instead of common plecos. They’re peaceful with other fish, attach to surfaces with their suckermouths, and require algae wafers and vegetable matter to supplement their diet beyond what grows naturally in the tank.

Swordtails

Swordtails are livebearers like guppies, named for the elongated lower lobe of the male’s tail fin. They’re hardy, adaptable, come in a range of color varieties, and generally peaceful in a community setting. They do best in groups with a ratio of more females than males to distribute attention and reduce stress on individual females. Like guppies, they breed readily, so plan accordingly if you keep mixed sexes.

That’s what makes freshwater fishkeeping endearing — there’s always more to learn, and the range of species available covers everything from a simple 10-gallon setup for a beginner to a 200-gallon species tank for someone who’s been at it for decades. Start with something manageable, learn the fundamentals, and let the hobby grow from there.