PAEDOCYPRIS SPECIES

Found in Perak, Selangor, Sarawak and Sumatra, among others, these "naked", or scale-less, fish (right) can be found only in highly acidic waters (about the same range as vinegar) in peat swamps and fringing freshwater swamps.

Mature fish in this group generally measure under 1cm, with the Paedocypris progenetica being the smallest aquatic vertebrate at 7.9mm long (for a mature female).

BETTA COCCINA SPECIES

Considered to be dwarf fighting fish (right), it generally does not grow larger than 5cm long. It can be found only in highly acidic waters (as low as pH 3.0) of peat swamps and fringing freshwater swamps in areas such as Peninsular Malaysia and central Sumatra.

The fish are atmospheric air breathers and drown if they cannot get access to water surfaces. The males are generally more colourful with longer fins.

ENCHELOCLARIAS SPECIES

Occasionally harvested for food, this fish species (right) can be found in Sarawak, Pahang and Central Kalimantan, among others.

Also known as the bladefin walking catfish, it generally does not grow larger than 20cm long. It is found in highly acidic waters of peat swamps and fringing freshwater swamps. It typically burrows into the peaty substrate and is not normally sighted.

PAROSPHROMENUS SPECIES

Harvested for the ornamental fish trade, this fish species (right) can be found in Terengganu, Pahang and central Sumatra, among others. It is usually found along weed-choked banks and deeper waters. Males are generally more colourful with longer fins. It is also found in highly acidic waters of peat swamps and fringing freshwater swamps.

Carolyn Khew