Last Updated on April 24, 2023 by Coral Realm

Saltwater Aquarium typesThis guide is a basic overview of the types of saltwater aquariums. The terms are used commonly in the fish keeping industry and it’s good for beginners to get to know what those differences entail. As we’ve mentioned already in our article on the best nano aquarium fish, it’s best for beginners to start with a medium sized tank that is large enough to accommodate mistakes in water quality error.


Saltwater Aquarium types:

There are four main terms you’ll here when it comes to types of saltwater aquariums. Those types of saltwater tanks are:

  1. Fish only tanks
  2. Fish only tanks with Live Rock (sometimes abreivieated to FOWLR)
  3. Full reef tanks
  4. Nano Aquariums

We’ll now explain each of these types of tanks in a little more detail for you:

Fish Only Tanks

This is the most basic type of saltwater fish tank. Typically very inexpensive essentially due to lack of ‘parts’ and also because there’s less lighting requirements.

While this is the easiest type of aquarium to start putting fish in, it’s not advised. You’ll have to have an incredible filter with this setup in order for the nitrogen cycle to complete. That’s because without corals or live rock, your aquarium will be fully dependent on a filtration system for good bacteria. Live rock and corals basically act as internal filter systems for the native fish. You’ll have to seriously stick to a rigid water change schedule to stop harmful nitrates from building up to a toxic level. That’s right, fish keeping is a science, you might want to check out our article on the nitrogen cycle for a insight in to the science.

So this type of tank is fairly obvious – it’s for keeping small amounts of (usually open ocean) tiny fish. These types of tanks are usually best kept for snails and crabs.  You’ll have to have snails to help control algae issues anyway.

Furthermore, there’s ethical issues when it comes to keeping fish in tanks that aren’t setup with natural decor. Artificial decorations might look nice but have no health benefit to the fish. Besides, there’s no reason to deny the beauty of natural plants and corals in aquariums, just check out these aquascaping examples.

Fish Only with live rock tanks – (FOWLR)

This type of tank is much better suited for most saltwater fish. It’s the same setup as the fish only tank except now you’ve introduced live rock and lighting such as aquarium specific LEDs. Live rock is natures filter, housing beneficial bacteria to keep water clean by aiding the nitrogen cycle. Certainly check out our articles on live rocks as it’s a really important part to get right. This is one of the best types of saltwater aquarium tanks to get started with.

Getting quality live rock, and SUSTAINABLE live rock, is the hardest part of the process. It may be tempting to buy live rock from a dealer that sourced it directly from the ocean but please consider the consequences. To get that live rock they’ve destroyed a habitat for the same fish you’re trying to create a nice environment for, it make literally no sense and you’ll think on that every time you look a the tank.

Live rock is just that, a rock. It’s deemed “living” because of the natural bacteria inside it and its natural ability to filter the tank through minerals and pores. A coral is an actual living thing.

There’s no reason why you shouldn’t use live rock, I think it makes a tank look much better and more natural.

A good rule of thumb is to have at least 1lb of live rock per gallon of water and it doesn’t come cheap either. Up to 5-10 dollars per lb. That could mean between $375 – $750 just to get started with a 75 gallon tank. And that’s the bare minimum of rock! Price is one of the main reasons people prefer to keep tropical or cold water fish over saltwater.

Reef Tank Setup

One of the most visually stunning saltwater aquarium types, the reef tank setup is exactly as it sounds. You’re trying to recreate a very fragile and delicate ecosystem and one that’s currently under threat; the coral reef. We try to encourage all our readers to sustainably source fish, live rock and coral. That means buying from sellers that grow/farm specifically for this industry, and do not take fish, rock or coral from the ocean.

Because a coral reef is such a delicate ecosystem even in an ocean, recreating it in a tiny glass box is incredibly difficult. This sort of tank is geared toward hosing corals, anemones, various invertebrates and coral dwelling fish. These are all incredibly expensive too!

Water conditions in reef tanks have to be perfect; top quality filters, protein skimmers, LED lighting, water supplements, plant feed, sand substrate, the list goes on and on.

Again, the benefits with a reef tank are huge. First of all, a reef tank is the most stunning tank out there, if you’re able to pull it off. Secondly, saltwater fish want access to rock and coral to feed on. Depriving them of that will reduce lifespan and overall happiness and vitality.

It’s generally recommended you start with tropical tanks, and then move toward having a FOWLR tank, before moving to a reef tank. It sounds crazy, but you really do need experience in this hobby. You wouldn’t go skiing down an expert slope without some practice! When you’re there though, perhaps you’ll even be looking after some of the best fish for advanced fishkeepers.

Nano Saltwater Tanks

The nano saltwater tanks are tanks under 30 gallons. Because the tanks are so small, any pollutant is easily noticeable (because it’s a greater % of the water). They are beautiful around the house but are extremely hard to look after because of their size. Usually these are best used for housing corals, breeding pairs or aggressive lone (but small) species.

We created a list of the best Fish For A Nano Reef Aquarium, if you want to give this type of aquarium a go.

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