15 gallon tank dimensions

Best saltwater fish for a 15 gallon tank

Setting up a saltwater tank is a hobby you can enjoy for years and years. One important aspect of having a successful aquarium is picking fish that are the right size for the tank and are compatible with each other. This guide will help you get started by sharing the 26 Best saltwater fish for a 15-gallon tank.

15 gallon tank dimensions

The dimensions for a standard rectangular 15-gallon tank are: 25 in. (63.5 cm) x 13.25 in. (33.7 cm) x 13.25 in. (33.7 cm), but you can also find name brand/designer models with slightly different footprints.

15-gallon tank dimensions

The Fluval Flex has a cube-like shape and is 15.94 in. (40.49) x 16.73 in. (42.49) x 15.94 in. (40.49 cm)

How to determine the best saltwater fish for a 15-gallon tank

1. Select fish that are there right size

One of the most important factors in determining the best saltwater fish for a 15-gallon tank is to pick fish that are relatively small now and will remain small, even as fully-grown adult fish.

2. Avoid fish that need too much space to swim

15-gallons is a perfect-sized tank for almost any room in your house, apartment, or even at work. But when you compare it to the ocean, it’s a tad bit on the small side. Perhaps not surprisingly, the fish that are perfect for a 15-gallon aquarium don’t need a lot of room to swim.

3. Skip the fish that require expert levels of care

In terms of care difficulty, let’s explore saltwater fish that aren’t that hard to keep. We want this to be a fun hobby, not a stressful situation where your fish are on life support.

4. Best attributes for saltwater fish for a 15-gallon tank

The best saltwater fish for a 15-gallon tank share the following attributes:

  • Small size as adults–ideally less than 4 inches in total length, smaller is good
  • Peaceful temperament–not likely to cause squabbles with other fish in your community tank
  • Gentle, slow swimmers–like waddling clownfish or perching gobies. The gentle swimming behavior often also connects with preferring a small, defined territory.

26 Best saltwater fish for a 15-gallon tank community

The best saltwater fish groups for a 15-gallon community tank are certain:

  • Gobies
  • Clownfish
  • Blennies (small)
  • Cardinalfish
  • Basslets
  • Damselfish

The first 5 groups of fish: Gobies, Clownfish, Blennies, Cardinalfish, Basslets, are all generally peaceful, community fish that could be kept together.

Best saltwater fish for a 15-gallon tank

But Damselfish would be best kept in a tank all to themselves due to their aggressive disposition.

Here is a table of the 26 Best saltwater fish for a 15-gallon tank:

Gobies (cleaner)NeonYellowlineSharknoseHybrid
Gobies (other)ClownCourt JesterYashaTwospot
Gobies (other)Black barred convictOrange stripe prawn
ClownfishPink SkunkOrange SkunkPerculaOcellaris
BlenniesTailspotTwo spot
CardinalfishPajama CardinalfishBanggai CardinalfishLongspineYellow
BassletsRoyal GrammaBlack Cap
DamselfishDominoYellowtail3-Stripe4-Stripe

In terms of stocking a 15-gallon saltwater tank, you could add:

  1. 2 clownfish (a pair)
  2. 1 Basslet
  3. 1-2 Cardinalfish
  4. 1 Goby
  5. 1 Blenny

Alternative community: Damselfish-only 15-gallon saltwater tank

Damselfish are gorgeous animals that are ideally suited for life in an aquarium. They are brightly colored, bold, hardy, and inexpensive. The only problem is that they don’t often play well with other fish in a community. So a great strategy is to start out with a damselfish-dedicated tank. You can mix damselfish species, but best not to add them with clownfish or other small, shy species.

How many saltwater fish can be in a 15-gallon tank?

A 15-gallon tank is a perfect size for anywhere between 1 and 6 saltwater fish, as long as compatible pairings of size-appropriate fish are properly acclimated over time.

Equipment needed for a 15-gallon tank

All saltwater tanks need some equipment. In the section below, I will share with you what equipment is absolutely required, what is recommended but not necessarily required, and what equipment is optional.

Required equipment

Aquarium lights are required equipment, but you can save money if you plan to have fish only
  • Lights – All tanks need lights of some sort. If your plan only involves saltwater fish, you can save some money and get an inexpensive LED fixture. If you want to corals, you’ll need a reef-quality light which will be fairly intense and more expensive.
  • Heater – for a tank this size, you will want a 75 or 100-watt heater
  • Equipment supporting biological filtration – there are a lot of options to choose from.
    • Sponge filters- simplest and least expensive option, need to be paired with an air pump
    • Hang-on-back – still relatively inexpensive, the power filters will suck water up into a special compartment where the water generally flows through a cartridge for filtration
  • Pump(s) – for circulation. Flowing, oxygen rich water is vital to any aquarium system, including a new saltwater tank.
    • Air pump – will literally blow bubbles into your tank – when the bubbles float to the top, they take the surrounding water with them, creating life-sustaining water flow
    • Powerheads – these submerged filters push water from one end to the other and are a great addition if you can afford the extra cost vs. an air pump.

Optional (but strongly recommended) equipment

  • A lid or mesh netting on top is strongly recommended as a physical barrier to keep startled fish where they belong–IN YOUR TANK

Truly optional equipment

  • A Protein skimmer is a very common and helpful piece of aquarium equipment that removes unwanted pollutants from your water–but you can certainly live without one. Learn more about protein skimmers here.

A few other related topics

Other stocking options (beyond saltwater fish)

This article focused in on the best saltwater fish for a 15-gallon tank, but there are a lot of other options out there for you to consider. Check out these other helpful articles to learn more about some of your other underwater options:

Best corals for beginners

12 Best reef safe shrimp

Best saltwater fish for similarly sized tanks

If you’re interested in seeing what options you have available for moderately larger or smaller tanks, check out these other stocking guides:

Best saltwater fish for a 10-gallon tank

Best options for a 20-gallon tank

30 gallon tank: saltwater fish options

Best saltwater fish for larger tanks

If you’re looking to see what saltwater fish you can keep in a larger tank, check out these other guides:

Best fish for a 40-gallon saltwater tank

Best fish options for a 50-gallon tank

Stocking guide for a 55-gallon saltwater tank

Frequently asked questions

Can 2 clownfish be kept in a 15-gallon aquarium?

2 clownfish can generally be kept in a 15-gallon aquarium, as long as they are the same species and are from one of the smaller species that include the common clownfish, percula clownfish and skunk clowns.

Can you use a 15-gallon tank for saltwater?

A 15-gallon tank is a nice size for a small saltwater aquarium. There will be enough room (volume of water) for several small saltwater fish and some invertebrates, like coral. Most spaces can accomodate a tank of this size.

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