site logo

Main Index > Detailed Fish Profiles > The Livebearers > Half beak
15 visitors reading profiles


This page will give a completely detailed profile of the selected fish, from A to Z. The profiled fish will be chosen randomly by Badman, and will come from the complete genre of tropical fish. New profiles are added on a regular basis. If you would like to submit a profile for the site please contact me. Don't forget to let us know you experiences with this fish by filling out the



Dermogenys pusilla

Dermogenys pusilla


    Some say this is a nervous fish others that it is a good community fish. They tend to stay near the surface and can jump out of the aquarium if not careful. Seen more and more for sale these fish will make an interesting addition to collection as long as you meet their needs.

Quick stats:

    Listed tank sizes are the minimum
    Size: Females up to 2.8 inches (7 cm), males smaller.
    Tank: 30" twenty gallon long (75 Litre). Long is better than tall.
    Strata: Top
    PH: 7.0 to 8.0
    Hardness: Medium hard to hard, dH range: 6 - 18°
    Temperature: 70 to 86°F (21 to 30°C)


    Order: Beloniformes
    Suborder: Cyprinodontoidei
    Family: Hemirhamphidae
    Sub Family: Zenarchopterinae
    Genera: Dermogenys

Common name:

    Half beak, Wrestling Half beak

Image gallery:

    Additional species photographs


    Badmans' Forum

    Found in fresh and brackish waters of Thailand and Singapore to the Greater Sundra islands.

General Body Form:
    Slender, long and Pike like with moderate lateral compression. The most obvious feature is the long protruding lower jaw. This jaw cannot move. The upper jaw is short and is connected to and moves with the skull. I have read that this is very unusual for a vertebrate. The Dorsal and Anal fins are set way back near the start of the tail the tail fin is somewhat oval in shape. The front bottom part of the Anal fins forms a Gonopodium, thus making the Half beak a livebearer. The first one is small and lies in line with the Ventral fins. The second Dorsal is much larger and lies in line with the similar shaped Anal fin. In juveniles and females the second dorsal and the anal fins are rounded, while in adult males they are elongated and pointed to separations at the tips.

wrestling half beak


    A very beautiful fish in its' own way . The most common coloration seen have a Silver to gray body with hints of Green or blue in it. The belly area is also Silver sometimes leaning toward White. The sides have the same sheen of Blue or Green as the general body appearance. The lower jaw has two colored lines on each side. One being Red and the other Black. The Dorsal,Anal and caudal fins are a pale yellow in color. Males Have a distinctive Red area in the front of the Dorsal fin. The iris in the eye is Bright Green. The females are generally paler in color overall .


    The tank should be as large as possible with the length being much more important than the depth. The rest of the tank can be planted anyway you like but some of the plants around the edges should reach the surface. The addition of some floating plants will also help mimic it's natural habitat. Leave some open space areas for swimming. Not the easiest fish to care for, they require the addition of some sea salt to maintain their best health. Provide gentle filtration with a slight water currant. . They will accept flake and frozen food, but they will fare better with live insects like mosquito larvae, fruit flies and daphinia if you can find it. The addition of a supplement containing vitamin D and A is an absolute necessity if you wish to breed them. Care must be taken when they are first introduced to the aquarium, if they get startled and dash about they may injure their lower jaw and this will lead to certain death.

    Shallow areas in the coastal areas of Southeast Asia. Found in both fresh and brackish water.

    Being a livebearer the Half beak gives birth to live young. Wild caught specimens can give birth to a couple of viable broods, but subsequent ones usually seem to fail. This is thought to be caused by the vitamin deficiency described above. During spawning the male will swim up to the female and nudge her sides with his beak. He will keep this up until she accepts him. The gestation period is also quite long and can last up to eight weeks. The broods are generally small. The newly born fry can be fed almost immediately on the finest flake food or baby Brine shrimp. At birth the upper and lower jaws are the same length which develop as the fry mature.

Your comments:


Please remember that the following comments are personal experiences and may or may not apply to your setup. Use them as guide to help better understand your fish, like us all individuals will behave differently under different circumstances.


From: Chetan
They are fantastic fish, quite like having a bonsai arowana. I had initially a mating pair of halfbeaks in my tank. While it is known that the males fight each other for territory etc., I however was surprised one day to find the male and the female fighting out of the blue. They went at it for over 10 minutes. Luckily enough I caught the action on camera ( And eventually the female gave birth to a fry. I totally did not expect that. When I used to feed the fish, the halfbeak would be the first to home (out-competing at time the bigger goldfish). It also used to peck at my finger when I dipped into water. The smart thing had actively associated me with food-time. Highly recommended fish for a community tank. Just make sure that there is a fair ripple in the tank.
From: Julie
Half beaks are indeed cool fish but it should be noted that they can be predatory. We introduced some 1" guppies into the tank and within 5 minutes we caught him swallowing one whole. He also was the demise of our ghost shrimp population - most were full grown. Our male was also a fin nipper. I wouldn't recommend them in a tank with smaller fish.

From: William
Reading up on the Half Beak I noticed a comment that they can only have a couple of broods before they can not have any more. They are guessing that it may be the result of vitamin deficiency's through diet, I am just guessing here but I once heard on a documentary,that nothing can stop a run of Salmon coming up a river faster that having Fluoride in the water. And another researcher states that he has discovered that Fluoride is a genome disrupter. So If you have Fluoride in your water maybe try filtering it for your tank.

From: Rory Judd
I have 2 half beaks about 5cm long 1 male and 1 female they are in a 180l tank, she snapped off the tip of her beak a day or two after I got them and she is fine and healthy about 2 months later. They fight over who gets to sit in the current from the power head and they sit in the current attacking the bubbles and anything else that come near them. All in all they are very cool fish and in my brackish tank with bumble bee gobys and they have added a lot of life I will be getting more.






Privacy Policy | Contact Badman's Tropical Fish
Copyright ©
All rights reserved. Reproduction of any portion of this website's content is forbidden without written permission.