The longfin zebra danio's fin length is set by an electrical signal through a potassium channel, rather than by a growth hormone. In lab work, blocking that channel with a drug while a longfin regrew a clipped fin held the new fin to normal length.
Caring for the longfin zebra danio
Keep longfin zebra danios in a group of at least five or six, in a tank of 11 gal (41 L) or more. They are constant, fast swimmers in the middle and top of the tank. Give them open swimming space and a current, since they are built for moving water.
They take cooler water than most tropicals, at 64 to 75°F (18 to 24°C) with a pH of 6.0 to 7.5. That makes them one of the few community fish for an unheated room. They eat just about anything, including flake, small pellets and live or frozen brine shrimp and bloodworms.
Fin nipping is the practical difference from the standard fish, since busy tank mates will find those long fins. Pick companions from the calmer end of a community list. Longfins are mostly peaceful themselves, but their energy can pester slow or long-finned tank mates.
Longfin zebra danios are egg scatterers that drop their eggs over the bottom and give no parental care. Breeding them is moderately difficult. Longfin is dominant, so one copy is enough, and a longfin crossed to a standard fish gives about half longfin fry.
Good to know
The longfin zebra danio has the same stripes or spots as the standard fish. Its dorsal, anal and tail fins are drawn out into trailing points. Shops sell longfins on both the striped and the leopard pattern, sometimes mixed in one tank. The mutation is regulatory rather than structural, switching on the potassium channel kcnh2a where it does not belong. That stretches out the period of fin outgrowth rather than changing where the fin is told to stop. Fin length is the visible change, and the striped or spotted pattern is inherited separately.
In the wild
The longfin zebra danio is a domestic mutation, and no wild fish carries it. Which hatchery first fixed the aquarium strain is not recorded, so it is a hobby line of uncertain origin. The longfin allele is also a laboratory fixture. The widely used Tupfel longfin (TL) stock strain carries it together with the leopard mutation. Those two visible traits let researchers spot mixed genotypes by eye.
Weekly picks
Tank mates
The longfin zebra danio is a mostly peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.
Is a longfin zebra danio a different species from the zebra danio?
No. A longfin zebra danio is a variety of the zebra danio, Danio rerio, and it wants the same tank, water and food as the species.
What size tank does a longfin zebra danio need?
A longfin zebra danio needs at least 11 gal (41 L). It spends most of its time in the middle.
What does a longfin zebra danio eat?
A longfin zebra danio eats just about anything. Offer flake and small pellets, with live or frozen brine shrimp and bloodworms.
How big does a longfin zebra danio get?
An adult longfin zebra danio reaches about 2 in (5 cm).
Does a longfin zebra danio need a group?
Yes. A longfin zebra danio is a schooling species and should be kept in a group, not singly.
How does a longfin zebra danio breed?
Longfin zebra danios scatter their eggs over the bottom and give them no parental care. Breeding them is moderately difficult, and a longfin crossed to a standard fish gives about half longfin fry.
1.2 in (3 cm)20 gal (75 L)72–79°F (22–26°C)
1.8 in (4.5 cm)18 gal (70 L)68–79°F (20–26°C)
2 in (5 cm)20 gal (75 L)68–79°F (20–26°C)
2.4 in (6 cm)18 gal (70 L)61–77°F (16–25°C)
1.5 in (3.7 cm)15 gal (55 L)64–79°F (18–26°C)
1.2 in (3 cm)11 gal (40 L)64–79°F (18–26°C)