Fish are how most people fall into this hobby. They’re the animal you picture when someone says “tank,” they’re available in every pet shop in the country, and they ask for a kind of attention that fits around a normal life. Feed them, keep the water right, and they’ll get on with being quietly fascinating.
They’re also where beginners get the most bad advice. The goldfish-in-a-bowl thing has done decades of damage, and “starter fish” is often code for “fish that will probably die while your tank finishes cycling.” So this page is the honest version: what to keep, what it actually needs, and which guide to read next.
Pet Fish: Start Here
Everything we’ve written about fish, grouped by where you are right now.
Choosing your first fish
- Choosing Your First Pet Fish — the full beginner walk-through, from picking a species to bringing it home
- Best Beginner Freshwater Fish — ten hardy species that forgive a new keeper’s mistakes
- Fish Tank Species and How to Combine Them — which fish actually get along, and which pairings end badly
- Micro Fish for Small Aquariums — nano species for tanks under ten gallons
Freshwater
- Freshwater Fish — the main hub for freshwater species and care
- Freshwater Pets — the wider freshwater world, including shrimp and snails
- How to Start an Aquarium — the step-by-step setup, including cycling
- Easy Freshwater Plants — beginner-proof plants that do real work for water quality
Saltwater and reef
- Saltwater Fish — the main hub for marine species
- Saltwater Fish for Beginners — the hardy end of the marine world
- Reef-Safe Fish — species that won’t eat the corals you just paid for
- Saltwater Aquarium Setup — what a marine tank really involves
- Reef Tank Setup — lighting, flow, and the rest of the reef puzzle
Tanks and tankmates
- Nano Tank Guide — the best setups under twenty gallons
- Nano Reef Tank Setup — small-scale reefkeeping without the heartbreak
- Pet Shrimp and Aquarium Snails — the cleanup crew most fish tanks are missing
- Aquatic Pets — everything in the water that isn’t a fish
Freshwater or Saltwater? The Only Question That Really Matters
Almost every other decision follows from this one, so it’s worth being honest about the difference.
Freshwater is where we’d send anyone starting out. The equipment list is short, the water chemistry is forgiving, mistakes are usually survivable, and the species range from a single betta to a planted tank full of tiny schooling fish. If you want a living tank in your house without it becoming a second job, this is the answer.
Saltwater is genuinely more demanding — more equipment, stricter parameters, and less room for a forgotten water change. It’s also spectacular, and the payoff is a slice of reef in your living room. We’d just rather you got a year of freshwater under your belt first. Plenty of people ignore that advice and do fine; they tend to be the ones who research obsessively before buying anything.
The middle path a lot of keepers take: start freshwater, add live plants once you’re comfortable, then decide whether reefkeeping is calling. Read Freshwater Fish and Saltwater Fish side by side before you commit to hardware.
What Every Fish Setup Needs
Species differ wildly. The basics don’t.
- More water than you think. Bigger tanks are more stable, not more work. A 20-gallon forgives errors a 5-gallon punishes.
- A cycled filter. This is the one beginners skip. Your tank needs weeks to grow the bacteria that process fish waste — adding fish before that is the single most common way a first tank fails.
- A heater, for most species. Room temperature is not the same as stable temperature, and swings stress fish more than the wrong number does.
- A test kit. You cannot see ammonia. Guessing is how tanks crash.
- Somewhere to hide. Plants, wood, rock, a cave — a fish that feels exposed spends its life stressed, and stressed fish get sick.
That’s genuinely it. Everything else is refinement. Our step-by-step aquarium setup guide walks the whole thing through in order, cycling included.
Beginner Mistakes We’d Rather You Skip
- Adding fish on day one. The tank isn’t ready. Wait for the cycle.
- Buying the fish before the research. That gorgeous fish at the shop may need six feet of tank and a shoal of twelve.
- Overfeeding. Uneaten food rots and poisons the water. Fish are much better at being hungry than we are at watching them be hungry.
- Too many fish, too fast. Stock slowly. Every addition is a load on a system that has to catch up.
- Trusting the tank a shop sells as a “starter kit.” Some are fine. Many are far too small for the fish pictured on the box.
Frequently Asked Questions About Pet Fish
What is the easiest pet fish for a beginner?
A betta in a properly heated, filtered five to ten gallon tank — or a small school of white cloud minnows if you’d rather watch a group. Both are hardy, characterful, and forgiving. Our beginner freshwater fish guide covers ten more.
How long do pet fish live?
Far longer than most people expect. Bettas commonly reach three to five years, many tetras hit five or more, and goldfish can outlive the family dog at ten to twenty years. Short lifespans are usually a housing problem, not a fish problem.
Can I keep just one fish?
Depends entirely on the species. Bettas genuinely prefer solitude. Most tetras, rasboras and corydoras are shoaling fish and become anxious kept alone — they need a group of six or more. Check before you buy one of anything.
Do pet fish need a filter and a heater?
A filter, essentially always. A heater, for most tropical species — the exceptions are coldwater fish like white clouds and goldfish, which do better without one.
How much work is a fish tank, really?
A settled freshwater tank is roughly a weekly water change and a few minutes a day of feeding and looking. The work is front-loaded into setup and cycling. Saltwater asks for meaningfully more, every week.
Where to Go Next
If you’re still deciding, start with Choosing Your First Pet Fish. If you’ve decided on freshwater, Best Beginner Freshwater Fish is the shortlist. If saltwater is pulling at you, read Saltwater Fish for Beginners before you spend anything.
And if it turns out the tank interests you more than the fish do, that’s allowed — plenty of us ended up here for the shrimp.