Fowlr Saltwater Tanks: 7 Reasons Why You Should Keep One

When deciding to set up a new saltwater tank, you will have a few different options.

One of the most popular options is a Fowlr or fish only with live rock saltwater tank. The term Fowlr is just an abbreviation given to it.

These setups are an in-between of a fish only tank and a full reef tank.

Think of them as a fish only tank with the addition of live rock.

For saltwater hobbyists who are not interested in keeping corals, a Fowlr tank is a way to go.

Let’s look at 7 reasons why you should keep a Fowlr saltwater tank.


1. More water movement

Water movement is crucial to maintaining the health of your saltwater tank. Regardless if you have a Fowlr tank or a full reef tank, proper water flow is required. With a Fowlr tank, you have the option of adding more flow which would be difficult to do in some coral tanks.

Depending on the fish you decide to keep, you can increase or decrease the water flow to suit them. Some fish, like the Copperband butterfly, do not like high water flow. Others like the Clown Tang love high water movement and are a very active fish.

The advantage a Fowlr tank has over a reef tank is you won’t need to be so picky in controlling the amount of water flow for both corals and fish. 

2. Saves money on lighting

Corals require proper lighting to survive and stay healthy. If you have a reef tank, plan to spend some money on a good set of lights. It’s not necessary to spend a fortune on lights, in fact, you can get some great reef capable lighting on a budget.

The type and quality of light are important. With a Fowlr setup, lighting is not a priority where there are no corals in the tank. You still want to make sure you have a nice light to show off your tank and fish colors, but ensuring it meets the specs for coral growth is not needed.

Some people like to buy very high quality and expensive lights for their reef tanks, but you can definitely save some money with lighting on a Fowlr saltwater tank. 

3. Can keep non-reef safe and aggressive  fish

This is my favorite reason to keep a Fowlr tank. There are several amazing fish that are considered not reef safe and can cause harm to corals. With a fish only tank, you are able to mix reef safe and non-reef safe fish together.

For example, the Emporer Angelfish is not reef safe, so you couldn’t keep them in a tank with corals. But they would be a stunning addition to a Fowlr saltwater tank. With a Fowlr tank, you could also keep certain aggressive fish that would normally wreak havoc in a reef tank. 

4. Easier to keep less established tanks

If you plan to keep a full reef tank, your tank will need to be well established and mature. The key to keeping corals is water stability and consistency. If your saltwater tank is fairly new and not mature, it will be easier to keep a Fowlr tank vs a reef tank.

Over time you can add corals to the tank as it matures, but you won’t have to worry about that with a Fowlr saltwater tank.

5. Water quality

Maintaining proper water quality within the normal parameters is important for all saltwater tanks. If you are keeping corals in your tank, they will require more pristine conditions versus a fish only or Fowlr tank. Corals are affected more by water fluctuations, temperature, etc.. 

Sometimes you can get away with less than ideal conditions in a Fowlr setup than you would with a reef tank. Fowlr tanks are less forgiving and usually require more maintenance and care.  

6. Dosing elements

Another reason to keep a Fowlr tank is you won’t have to worry about dosing elements as much as you would with a reef tank. Certain elements like Calcium, Magnesium, Alkalinity, will need to be kept within limits for corals to survive.

There are some great supplements on the market that will help you keep these elements in check. Your corals will naturally use up these elements which will need to be replaced in the tank.

Some people choose to use a dosing pump to distribute a specific amount of supplement throughout the day to balance out the amount being used by the corals.

If you are not interested in dosing elements, a Fowlr tank is a way to go. 

7. Less bioload and equipment

Depending on the amount of fish and corals you have, the bioload and filtration required will fluctuate. Not all tanks are going to be the same. It’s safe to say that a saltwater tank that is set up as a full reef tank, will have a higher bioload than a Fowlr tank with only a few fish in it.

Of course, if your tank is packed full of fish, your bioload will be high as well. It’s important to not have too high a bioload for your tank. Keeping a Fowlr tank with no corals is a way to do that. Also, many coral tanks will use certain equipment to keep water quality in check.

Things like reactors, sumps, refugiums, and other pieces of equipment are used on reef tanks. It can get out of hand very easily and the amount of gear you can add to a reef tank is impressive. But not all of it is necessary.

With a Fowlr tank, you will still need equipment on the tank. Just not as much as a reef tank. You can get away with a pretty basic system with little equipment if you want to.


There are many reasons to keep a Fowlr tank. These are just a few that I mentioned. There are pros and cons to keeping one. If you want to have a great mix of colorful fish that are not reef safe, then Fowlr is the way to go. There are plenty of different rocks available to build your perfect aquascape.

With a Fowlr tank, you won’t need to worry about coral placement and constantly moving them around to find that perfect location for them. Many people prefer Fowlr tanks over reef tanks for many reasons including the ones I mentioned here.