FOWLR aquarium fish

FOWLR stands for fish-only with live rock: a saltwater tank built around fish rather than corals. These species eat or nip corals and inverts, so they belong in a fish-only setup rather than a reef. Expect bigger, bolder fish like large angels, triggers, lionfish and puffers. Each profile lists tank size, temperament and diet.

Tank size: 32–300 gal; 32 gal (120 L) to 300 gal (1,135 L); half the list needs 151 gal (570 L) or more
Temperature: 73–81°F; 23–27°C, most of the list
pH: 8.1–8.4; Most of the list
Difficulty: 1 easy; 24 medium · 26 difficult
Temperament: 5 peaceful; 32 mostly peaceful · 14 aggressive

51 species

Start here

The classic FOWLR stocking

A fish-only tank with live rock is built around fish that would wreck a reef. The Picasso triggerfish reaches 11.8 inches (30 cm), lists 180 gallons (680 liters) and rearranges the rockwork. The dogface puffer is a 13 inch (33 cm) fish for 151 gallons (570 liters) that learns to beg at the glass, and the porcupine puffer is its spiny cousin at 11.8 inches (30 cm). The volitans lionfish reaches 15 inches (38 cm) and eats any fish it can swallow. The bluehead wrasse is the easy, active fish of the group at 7.1 inches (18 cm) for 74 gallons (280 liters). The raccoon butterflyfish reaches 7.9 inches (20 cm) and picks at polyps, which is the whole reason it is here.

The rule

Why these fish are not reef safe

Every fish on this page is marked not reef safe. The triggers, puffers, boxfish and the big wrasses eat invertebrates: snails, hermit crabs, shrimp and clams are food to them. The butterflyfish and the large angelfish nip coral polyps and clam mantles. Neither habit trains out, so the tank is fish and rock, with no clean-up crew that can be eaten, and the filtration is sized for big, messy eaters, since a lionfish or a grouper produces waste on a scale a reef never sees.

01
They eat inverts
Triggers and puffers crush snails, crabs and shrimp
02
They nip coral
Butterflyfish and angels pick at polyps
03
They need room
Most profiles list 100 gallons (380 liters) or more
04
They foul water
Big eaters need big filtration and a lid

Triggers and puffers

Triggers, puffers and the teeth that never stop growing

A puffer's beak keeps growing, so it needs hard food, clams in the shell and whole shrimp, or the teeth overgrow. The stars-and-stripes puffer reaches 19.7 inches (50 cm) and lists 180 gallons (680 liters), the map puffer 23.6 inches (60 cm) in 238 gallons (900 liters). The triggers are marked aggressive across the board. The wedgetail triggerfish is the manageable one at 11.8 inches (30 cm) for 106 gallons (400 liters), the bursa triggerfish lists 9.8 inches (25 cm), and the clown triggerfish is the expert's fish, marked difficult and aggressive at 19.7 inches (50 cm) with a 300 gallon (1,135 liter) minimum.

Angels and butterflies

Large angelfish and butterflyfish

The big Pomacanthus angels are the showpieces of a FOWLR tank and outgrow most of them. The emperor angelfish reaches 15 inches (38 cm) and lists 185 gallons (700 liters), the koran 15.7 inches (40 cm) in 132 gallons (500 liters). The Red Sea angelfish is the compact choice at 7.9 inches (20 cm) for 125 gallons (475 liters), marked medium. The butterflyfish are calmer. The golden butterflyfish is marked peaceful and social at 9.1 inches (23 cm) for 151 gallons (570 liters), the pearlscale butterflyfish 5.5 inches (14 cm) for 75 gallons (285 liters), and the threadfin butterflyfish 9.1 inches (23 cm) for 79 gallons (300 liters).

Lionfish and groupers

Lionfish, groupers and the predators

The dwarf lionfish are the ones that fit a normal tank. The fuzzy dwarf lionfish reaches 7.1 inches (18 cm) and lists 50 gallons (190 liters), the dwarf zebra lionfish 9.8 inches (25 cm) in 60 gallons (227 liters), and the radiata lionfish 9.4 inches (24 cm) in 70 gallons (265 liters). Their spines are venomous, so hands stay out of the tank. The groupers are the fish that need a wall: the panther grouper reaches 27.6 inches (70 cm) and lists 300 gallons (1,135 liters), the lyretail grouper 31.5 inches (80 cm) in 291 gallons (1,100 liters). The sailfin snapper is a 23.6 inch (60 cm) fish for the same tank. All of them eat any fish that fits in the mouth.

By the numbers

Smallest

Largest

FAQ

Common questions

What does FOWLR mean?

Fish only with live rock: a saltwater tank with rock for filtration and territory but no corals, stocked with fish that would eat or nip a reef.

Can a FOWLR tank have a clean-up crew?

Not a lasting one. Triggers, puffers and the big wrasses eat snails, hermits and shrimp. Algae control falls to the keeper, or to a fish such as a tang that leaves inverts alone.

What size tank does a FOWLR need?

From 50 gallons (190 liters) for a fuzzy dwarf lionfish or 74 gallons (280 liters) for a bluehead wrasse, but most fish here list well over 100 gallons (380 liters), and the groupers and clown triggerfish list 300 gallons (1,135 liters).

Are lionfish dangerous?

Their spines are venomous and a sting is painful. Keep hands clear when working in the tank, and soak a sting in hot water while you seek medical advice.

Can I mix triggers and puffers?

In a large tank, one trigger added last with a puffer that is already established. The triggers are marked aggressive; the dogface, porcupine and stars-and-stripes puffers are marked mostly peaceful. Two triggers is a fight.

Do FOWLR fish need live rock?

Rock gives them territory to claim and carries the bacteria that process the waste of big eaters. It is the LR in the name, and the tank runs better with it than without.

Index