Also known as the Brunei Beauty and Ikan Pelaga Brunei, the Betta Macrostoma(literally “big mouth”) is a mouthbrooding species with a unique history. With the fast social and economic development in Brunei, it was commonly held for over 50 years that the fish was extinct. In 1981,B. macrostoma was”rediscovered” in one of the waterfalls of Brunei Darussalam,leading to fresh excitement and interest in this species. As of this writing, International Union for Conservation of Nature and Natural Resources has classified the Macrostoma as “vulnerable”.
The Macrostoma can be housed in pairs or kept in special species or certain community set ups. Pairs do very well together long term, and should be kept in well-planted, well-covered tanks of at least 40 gallons. When keeping Macrostoma in pairs or in a group situation, it is not uncommon for spawnings to occur unnoticed,and for fry to be discovered in the tank by the aquarist during normal tank maintenance.
Although often labeled a”difficult” fish,Macrostoma can usually be kept very well in most water chemistries, as long as the water quality is well maintained; however the highest incidences of spawning occur in soft water with a pH below6. What seems to be more important to Macrostoma is consistency- they do not do well with shifting water perimeters. They are best kept in the 70 – 75F degree range, and it is imperative that their tank is kept very well covered! Macrostoma is an ingenious jumper with a penchant for finding the very smallest openings in a tank hood, and escaping from them.
The fish is omnivorous and does well on a varied diet such as frozen beef heart, bloodworms, daphnia, brine shrimp, and many varieties of prepared and dried commercial foods.
Male Macrostoma are much more vividly colored than the females, displaying brilliant orange-red with highly contrasted black and white markings during courtship and spawning. The female is a rather drab,silver-brown fish with two very distinct lateral bands. It is often possible to seethe female’s ovum by shining a light on her.