Top Fish for Starting a Tropical Freshwater Aquarium

the best starter fish for a tropical aquarium

The Spruce

Nothing is more exciting than adding new fish to a newly set up aquarium. However, the fish you choose will have a big impact on your tank's success or failure. Unfortunately, many new fish owners make the wrong choices, lose some or all of their fish right away, and give up on keeping fish.

The two biggest errors made when stocking a new aquarium are adding too many fish at a time and choosing incompatible species. Tip the scales in your favor by following these basic, but important, steps to stock your new aquarium correctly.

How Many Fish?

When you are considering the many beautiful fish at the pet shop, remember one word—moderation. In most cases, only two or three fish should be introduced to a tank initially. Once the nitrogen cycle is established and the tank is stable, additional fish can be added each week. However, the same rule applies when adding the next round of fish. Moderation: you must add only a few at a time.

So how many fish can you add? That depends on the capacity of the aquarium. In general, fish need 1-2 gallons of water for each inch of adult body length. Remember that most fish sold in fish stores, except for smaller fish like guppies and tetras, are not at their adult size in the stores. Please read the information tags on the aquarium for each fish you are interested in to see how big it will be as an adult. Some fish sold in the shops, like oscars or catfish, might currently be only a few inches, but can grow to be a foot long as adults!

Factors in Choosing Fish

Fish owners tend to opt for fish with the most physical appeal. Pretty fish are sometimes acceptable beginner choices, but there are other more important factors to consider. A beginner fish should have these qualities:

  • Tolerates a variety of water conditions, particularly the conditions during startup
  • Accepts a variety of foods, and are easy to feed
  • Does not grow to be overly large
  • Not aggressive
  • Compatible with a variety of other fish (unless you're creating a single species tank)

Small schooling fish are generally good first fish, but take care to not add an entire school at once if the tank is new. If you want more than one species, do not start them all at the same time. Instead, build one school up before starting the next species. For schooling fish, it is preferable to have 5 or more fish in the school to keep them happy, but start with 3, and introduce more after the tank goes through the nitrogen cycle.

Tetras, for instance, are a schooling fish to avoid in any new tank. Most are more sensitive to water conditions than other fish, and often will not survive the initial start-up cycle. It’s generally best to wait until the tank is mature before adding Tetras. Danios and barbs are better schooling fish to start with in a new aquarium.

Good First Fish

  • Barbs: Cherry, Gold, Rosy, Ruby, Purple, and Tico Barbs are good. Avoid Tinfoil and Spanner Barbs due to their larger size, and avoid Tiger Barbs because they tend to nip and be quarrelsome.
  • Danios: Zebra, Leopard, and Pearl Danios are good. Avoid Giant Danios, due to their size.
  • Rasboras: Harlequins and Scissortails are good choices.
  • Catfish (some varieties): Bronze or Gold Corydoras, Spotted Cory, Bandit Cory, and Panda Cory, are good. Avoid Plecos unless you have a large tank or have a local pet shop that will take them back when they get too large for your tank. Avoid upper water catfish (those that are not bottom dwelling) as they will grow larger than the size they are sold at in the fish stores.
  • Rainbowfish: Boesmans, Neon, and Celebes are all good.
  • White Cloud Mountain Minnows
  • Gouramis: the dwarf gouramis is a little more delicate, but blue, gold, opaline and pearl gouramis are larger, colorful fish that can be kept in community aquariums.

Although the list seems small, there is quite a variety to choose from. Once your tank matures, you can branch out into other species of fish.

Wrong First Fish

If you are wondering why your favorite fish isn't on the "good first fish" list, here are some popular fish that you should not add to your new freshwater aquarium.

  • Catfish (some varieties): Many catfish are sensitive to the start-up cycle, or they grow too large to be good first fish. For example, the common Pleco is a hardy fish, but it grows to be very large. The Otocinclus is small but very sensitive to toxins that are usually present in a newly started tank.
  • Goldfish: Goldfish are cold-water fish that produce copious amounts of waste, which means that they require a larger tank all to themselves; and yet, the proverbial goldfish bowl is not an ideal home for the goldfish. If you want a goldfish, give it a nice roomy tank of just goldfish.
  • Live bearing fish: If you have children, you may be tempted to get live bearing fish. Because they require special conditions (most notably salt in the water) and are more susceptible to disease, they are not ideal first fish. If you do opt for live-bearing fish, choose one species only, such as mollies or platys. Guppies are typically more sensitive than these to new tank water conditions.
  • Cichlids: most cichlids tend to be aggressive and get rather large. These are best suited for experienced fish keepers with larger aquariums.

At the Fish Shop

Ask the fish store associate what the adult size is of each fish you are interested in, as they may not be full grown in the store. Be sure you are not buying too many fish at one time, and that the fish you buy are compatible with each other, and with those you already have at home. Only add two or three new fish to your aquarium at a time, and then wait a week or two before adding new ones, until you reach the maximum number of fish that can be kept in your size of aquarium.

Now that you've decided on the species of fish, there is one more important step–choosing healthy individuals. When you go to the shop, don't accept just any fish. Look them over carefully. Avoid fish with wounds or nipped fins as they are likely to be more susceptible to disease. Check the eyes; cloudy eyes are a sign of poor water conditions and or disease. Also avoid fish with sunken bellies, as they have been chronically underfed and may be suffering from a disease.

Avoid fish with fuzzy or ragged fins, or signs of disease such as patchiness or white spots on the skin. Make sure the fish is swimming normally, with the fins erect, and be sure it eats actively when fed. This will give you the best chance of buying a healthy fish.