Forktailed Rainbow Fish, Pseudomugil furcatus - Fun, Easy and Stunning

The Forktailed Rainbow Fish, Overlooked, Hard to find, but well worth a Look

Forktailed Rainbow Fish or blue eyed rainbow fish

The Forktailed Rainbow Fish or Pseudomugil furcatus is a very attractive species with bright yellow stripes on the top and bottom of the body in breeding season.  Two upturned almost wing-like pectoral fins, bright yellow in color along with bright yellow dorsal fins in breeding season make this little gem a great attrition to any Community Aquarium.

Less than 2 inches when fully grown, this small rainbow is a truly beautiful fish that fits in well with other small shoaling fish in a well planted community aquarium.

  Providing that this fish is transferred over to its new aquarium home slowly, they will adapt to a wide range of water conditions ranging from soft and slightly acidic water to hard and alkaline.

Another great advantage to the Forktailed Rainbow Fish, is their feeding requirements, they have almost no special needs.  Best case, they will color up for breeding with small live food supplemented once or twice per week.  However, this community shoaling fish survives well on high quality dry food, happily eating along with tank mates. 

The Forktailed Rainbowfish is a very active fish, not only fast, but agile as well, swimming, twisting and turning in and out of plants playfully all day.  It is best to keep 2 females and 1 male or 2 males and 4-6 females for best and most active displays.  Remember, as shoaling fish, they need odd numbers and as large of a group as you can afford in cost and tank space.


Family:  Pseudomugilidae (Rainbow Fish)


Sub Family:  Pseudomugil


Native Habitat:  New Guinea


Male and Female Differences:  The males can be distinguished by their clearer colors and the striking fin shape (curved and almost wing-like) which are bright yellow.


Size: just under 2 inches in captivity


Best Kept:  These shoaling fish can be kept in an average sized community aquarium.  They prefer plenty of feathery-leafed plants.  Floating plants and a dark substrate will not only bring out their colors to best effect, but the fish will be more comfortable and calm, with this touch of their natural environment added.  Live plants are necessary for this fish to thrive.


Aquarium Behavior:  The Forktailed Rainbow Fish is a very elegant and peaceful addition to any community aquarium.  This fish does best in shoals of 5-9 and should not be kept in just a pair.  They leave other community aquarium fish alone, never nip or chase.  They are a middle zone fish and are in motion as long as aquarium lights are on.


Temperature:  Anywhere from 74F – 80F with 77 as preferred norm.


Water Conditions:  pH from 6.5 – 8 and hardness not particularly important, but prefer medium to hard water.


Food:  Forktailed Rainbow Fish will thrive on occasional small live food, combined with good quality dry flake food.


Breeding:  Pseudomugil furcatus usually mate within the shoal and lay their eggs among feathery-leafed plants.


How to Breed Pseudomugil furcatus, The Forktailed Rainbow Fish


Over the last 10 years, this remarkable member of the Rainbow Fish family has faded almost completely from the Home Aquarium scene.

  It is unfortunate, because not only is this remarkable fish one of the easiest of the Rainbow Fish to keep in a community aquarium, it is also one of the easiest of its kind to breed.

The Pseudomugil furcatus is easy to breed, beautifully colored and relatively hardy.  They are not fussy with regard to hardness or pH and seem to do well in a very wide range of water conditions.


Best Breeding Procedure:  Use 2 males and 6 females, each male will set up his own “territory” in the well planted breeding tank.  One of the males will take possession of a fine leaved plant or breeding mop at a far end of the tank.  You will notice that the females will stay in the middle of the aquarium during this mating ritual; the other male may take possession of another plant of breeding mop at the other end of the tank.


You must get up at sunrise, or cause the lighting system in the breeding tank to simulate dawn, for it is then that the males will display for the females (worth getting up for, they become quite beautiful in their dances).  Occasionally the males may have a brief skirmish for dominance, but they tend to ignore each other (this is why we suggest 6 females).

Eventually a female will follow one of the males back to his chosen plant or breeding mop to spawn.  You will know they are spawning when they dip to the lower reaches of the tank and swim up into the plant or mop close next to each other.  As they reach close to the top of the plant, they push into each other, and release eggs and milt together.

The most difficult part about breeding this remarkable fish is the wait for the eggs to hatch.  It will take at least 14 days.  There is a real chance of losing the eggs to fungus if left in the breeding tank.  Best results are had removing the eggs to sterile water tank, with fungus treatment, much as you would with Angel fish.


Rearing the Fry:  The fry are unusual among small egg layers in that they are free swimming and self-sufficient at time of hatching.  They are large enough to accept live baby brine shrimp and powered dry food.

Use a sponge filter in the fry rearing tank after 3 weeks, change 20% of the water each week, and feed small amounts of varying foods 6 times a day.  With luck and good attention to detail, the fish will be sexable at 3 months and over an inch long.


Note:  These fish are short lived in nature, and because of this they mature quickly, breed young and are over the hill by one year of age.  Males are prime at about 8 months, after 1 year to 15 months they will develop a pigeon chest, at which time they are too old or mature to breed.  However many Forktailed Rainbow Fish live to be very old fish in a community aquarium, just no longer prime for breeding.


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