TankBud

Freshwater blenny

Salaria fluviatilis

FreshwaterFish

Freshwater blenny (Salaria fluviatilis)
Olivier Croissant · CC BY 3.0

Care at a glance

Temperature
54–68°F
12–20°C
pH
7.0–8.0
Adult size
5.9 in
15 cm
Minimum tank
25 gal
95 L
Temperament
Mostly peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Carnivore
Difficulty
Difficult
Breeding
Cave spawner
Rarity
Very rare
Family
Blenniidae
Origin
Europe, North Africa

Overview

The freshwater blenny is a territorial bottom fish for a cool, rocky freshwater tank. It is a fish for experienced keepers.

Did you know

Almost every blenny species lives in the sea, so the freshwater blenny is a real oddity. It spends its whole life in inland rivers and lakes. It is one of only a handful of truly freshwater members of a large, mostly marine family.

Caring for the freshwater blenny

Give one freshwater blenny a tank of 25 gal (95 L) or larger with a long footprint, so it has enough territory. It needs a floor of rock and cobbles with plenty of caves and crevices.

It is a cool-water fish, so keep it at 54 to 68°F (12 to 20°C). Let the temperature run toward the low end in winter. A summer chiller or a naturally cool room is often needed to hold it down. Give it clean, hard, alkaline water at a pH of 7.0 to 8.0, with steady, oxygen-rich flow.

It hunts small living prey and usually refuses dry flake. Feed frozen and live foods, such as bloodworms, small snails, shrimp and insect larvae.

Keep it singly or as a single pair, since males defend a home cavity and spar with rivals. Away from its own kind it is fairly peaceful and ignores fish that stay up in the water. Pick active, cool-water swimmers as companions rather than other floor dwellers.

Males grow larger than females. The female lays her eggs inside a crevice or under a rock. The male then cleans, fans and guards the clutch alone until the fry hatch. Reliable breeding in home aquariums is not established.

Good to know

The freshwater blenny belongs to Blenniidae, the combtooth blenny family. It has a goby-like shape and habits, but it is a true blenny rather than a goby. A single long dorsal fin runs the length of its back. The species is considered threatened across much of its range.

In the wild

The freshwater blenny lives in the rivers, streams and lakes around the Mediterranean, across southern Europe, the Near East and North Africa. It is usually found in clear, flowing, rocky water.

Common questions

What size tank does a freshwater blenny need?

A freshwater blenny needs at least 25 gal (95 L). It spends most of its time in the bottom.

What temperature and pH does a freshwater blenny need?

A freshwater blenny is comfortable at 54–68°F (12–20°C) with a pH of 7.0–8.0.

What does a freshwater blenny eat?

A freshwater blenny eats frozen and live foods, such as bloodworms, small snails, shrimp and insect larvae. It hunts small living prey and usually refuses dry flake.

How big does a freshwater blenny get?

An adult freshwater blenny reaches about 5.9 in (15 cm).

How can you tell a male freshwater blenny from a female?

Males grow larger than females.

How does a freshwater blenny breed?

Freshwater blennies lay their eggs inside a crevice or under a rock. The male cleans, fans and guards the clutch alone until the fry hatch. Breeding them in a home aquarium is not established.

Related species