Catfish of the Month Right Arrow June 2014

Mystus aff. gulio    

Article © Heok Hee Ng, uploaded June 27, 2014.

Setting up a brackish-water biotope presents its own set of problems for the catfish enthusiast, since one faces a dearth of choices when it comes to choosing appropriate siluriform inhabitants. The fact that many catfishes that live in such habitats are ill-suited for the average tank further compounds the problem: ariids and marine plotosids grow too large for the general aquarium (not to mention that they require fully marine habitats when adult), and very few catfishes can tolerate the amount of salt necessary in a brackish water setup. Eel-tailed banjo catfishes such as Platystacus cotylephorus are a viable option, but for those who want something that better fit an Asian biotope, and whose signs of life consist of something more than just lying on or burrowing into the substrate, there is always Mystus aff. gulio, the subject of this month's article.

Before we get to the husbandry that is the heart of this article, it is necessary to digress a little to explain why this fish is not simply identified as Mystus gulio, a species described from the lower reaches of the Ganges River. The fish recognized as M. aff. gulio here is a Southeast Asian species that differs chiefly from its Indian counterpart in growing to a slightly smaller size (under 15 cm SL vs. just beyond 20 cm SL) and being more grayish (as opposed to greenish) in life. Whether these are differences that truly reflect different species remains unconfirmed (if they are, then the Southeast Asian species should be called M. abbreviatus).

In the wild, M. aff. gulio is found in the extreme lower reaches of river systems, where the water is brackish (or very nearly so), with individuals being frequently encountered even out at sea in shallow coastal waters (the only other bagrids known to be found in similar habitats are M. velifer and M. wolfii). Unlike almost all other members of the Bagridae, M. aff. gulio does best in brackish to marine waters; although this species can be maintained permanently in pure freshwater aquariums, we do not know if there may be any adverse effects on the health of the fish in doing so. Like most bagrids, they are easy to feed and will readily take live, frozen or dried food (variety is the key to a healthy fish here).

Mystus aff. gulio are highly gregarious when young and juveniles will school tightly. With age, they become less sociable and form very much looser aggregations, to the point where individuals will sometimes swim together, but will more frequently just tolerate each other and settle in their own corners of the tank. As with most mid-sized bagrids, tankmates that are too large to be eaten (e.g. archerfishes and larger gobies) are pretty much ignored.

Mystus aff. gulio are very infrequently encountered in the aquarium trade. They are very common throughout their native range, but their drab coloration gives them very little appeal as aquarium fish. Even in Singapore, many of the individuals I have seen for sale as aquarium fish show up as bycatch amongst feeder platies that are caught by the hundreds from the large tidal drains, rather than as targeted species.

Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Down arrow Cat-eLog Data Sheet
Scientific Name Mystus aff. gulio   
Common Name
Pronunciation miss tuss
Etymology The generic name is probably derived from the Latin mystax, meaning moustache, in reference to the long barbels. It was first used by Scopoli in 1777 making it a very old genus that has included many catfishes from throughout the world at one time or another. 
Down arrow Species Information
Size 200mm or 7.9" SL. Find near, nearer or same sized spp.
Identification Fishes of the genus Mystus Scopoli are small to medium-sized bagrid catfishes occurring in South Asia. Roberts (1994) recognized Mystus to have an elongate cranial fontanel reaching up to the base of the occipital process, long maxillary barbel, very long adipose fin, 11–30 gill rakers on the first gill arch and 37–46 total vertebrae, about equally divided between abdominal and caudal regions. He included only eight species under the genus. Mo (1991) characterized the genus to have a thin needle-like first infraorbital, twisted and thickened metapterygoid loosely attached to the quadrate by means of ligament or a small extent of cartilage. Jayaram & Sanyal (2003) and Ferraris (2007) respectively listed 44 and 33 species of Mystus as valid.

The true M. gulio grows much larger than this species, and is a more greenish (vs. grayish) color.
Sexing Males have an elongate genital papilla in front of the anal fin.
Down arrow Habitat Information
Distribution Generally restricted to estuarine reaches of rivers in Southeast Asia.
pH 6.0 - 7.8
Temperature 22.0-27.0°C or 71.6-80.6°F (Show species within this range)
Other Parameters Prefers brackish water, although it can do well in fresh water.
Down arrow Husbandry Information
Feeding Easily adapts to a wide variety of frozen and prepared food in the aquarium. May eat very small fish.
Furniture The tank should be furnished with ample driftwood as hiding spaces.
Compatibility Compatible with most fishes, although very small fishes will be eaten. Ideal tankmates include larger barbs and rasboras in an Asian biotope setup or an Asian brackish water setup with scats, archer fishes and gobies.
Not overtly territorial, so more than one individual can be kept together.
Breeding Not reported.
Breeding Reports There is no breeding report.
Down arrow Further Information
Registered Keepers Keeping this species? Why not .
There are 3 registered keepers, view all "my cats" data.
Wishlists Love this species? Click the heart to add it to your wish list.
There is no wish to keep this species.
Spotters Spotted this species somewhere? Click the binoculars!
There are 3 records of this fish being seen, view them all.
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Last Update 2007 Jun 27 12:54 (species record created: 2014 Jun 27 20:40)

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