Matt Clarke looks at an attractive barb that's being sold as Barbus mahecola in the UK's aquatic shops.
Common name: Mahecola barb, Mascara barb
Scientific name: Puntius assimilis
Trade name: Puntius sp. "mahecola"
Origin: The type specimens of P. assimilis were collected in the Nethravati River in an area previously known as South Canara in Karnataka State in India. The fish have also been collected immediately downstream of waterfalls in the Chalakudy River in Kerala, India. P. mahecola, the species this fish is usually mis-sold as, is found across most of the state of Kerala in South India, but generally occurs in the coastal floodplain rivers and possibly the foothills, according to recent studies. Pethiyagoda and Kottelat say that it lives in muddy slow-flowing waters about 2m/6'6" deep.
Aquarium: Hardy and easy to keep, but appreciates good oxygen levels and plenty of free swimming space. Keep a group of six or more fish, and outnumber males 2:1. May eat tiny fish, such as Zebra danios, when fully grown, but leaves other fish alone. Will eat soft-leaved plants.
Water: Very adaptable, so hard or soft conditions should be fine, providing extremes are avoided.
Notes: This fish should not be confused with the real Puntius mahecola. Recent research (2005) has shown that P. mahecola is a distinct species, and not actually a synonym of P. filamentosus as previously believed. Many previously suggested that "mahecola" was a geographic race or sub-species of filamentosus rather than a distinct species, since this form has more red on the caudal fin and brighter adult colouration than the typical filamentosus. P. assimilis is a distinct species and sits in a species group alongside filamentosus, singhala, tambraparnei, aurulius, srilankensis and exclamatio. P. mahecola is not a member of this group and real ones actually look very different to the assimilis being sold in the trade under the mahecola nametag.
Identification: Easily confused with Puntius filamentosus and P. singhala. The mouth of P. assimilis is quite different to that of filamentosus and singhala. In assimilis it is inferior, while filamentosus and singhala have a subterminal mouth. The body lacks prominent markings apart from the spot which sits above the origin of the anal fin. P. singhala (which has also been imported into the UK) lacks distinct markings on the lobes of the caudal fin.
The real P. mahecola looks rather different and is quite simple to tell apart. It has a much smaller black spot on the caudal peduncle and it is situated much more posteriorly than the spot in any of the filamentosus group. In assimilis, for example, the spot sits above the anal fin. True mahecola have rarely been seen.
Sexing: Easy. Females are fairly plain. Males have longer dorsal fins and brighter colours than females, developing lavender colours and greatly extended dorsal fin rays. Spawning tubercles form on the opercula of males.
Breeding: I have bred the related P. filamentosus successfully and found them to be quite prolific spawners. Males develop bright colours during courtship and drive females into the plants where they scatter their eggs. The eggs hatch after a couple of days and are large enough to take nauplii within a couple of days. The young fish develop dark vertical bars which gradually disappear by the time the fish reach 4-5cm/11/2"-2" in length. A cold water change will trigger spawning in conditioned fish. P. assimilis should have similar spawning behaviour, I would imagine.
Availability: These fish were on sale at Maidenhead Aquatics in Harlestone Heath.
Price: Around 5-10 for a small one.
This article was first published in the August 2004 issue of Practical Fishkeeping magazine. This article was subsequently updated in 2005 following the redescription of P. mahecola and the revision of the filamentosus complex by Kottelat and Pethiyagoda.