The tropic is a fascinating place to visit and if you are a tropical fish enthusiast, a paradise. The abundance, profusion, and exuberance of life are incredible. Every niche is exploited even in the worst polluted environment of man’s creation. Having spent my childhood in this environment, I had the chance to cultivate my fascination for nature and especially for the aquatic realm. The place I called home for the first sixteen years of my life is Kuching, which is the capital of the Malaysian state of Sarawak, on the island of Borneo.
The island of Borneo can be divided roughly into three distinct zones that are the coastal/mangrove forest, the lowland peat swamp forest, and the montane forest. In the coastal/mangrove forest zone, the species that are of interest to the aquarist are brackish water fishes (mud skipper, archerfish, bumblebee goby, puffer, monos, etc.) and of course the marine species. In the lowland peat swamp forest, where the waterways are coffee-colored has a pH of 4, live the barbs, rasboras, bettas, loaches, gouramis, catfishes, shrimps, crabs, halfbeaks, etc. A lot of these same species can be found in the montane forest zone waterways which are usually clear, fast following, and have a pH of about 8. Additional species that live only in the montane forest zone are the danios, sucker mouth loaches, and few others.
It is quite amazing that the water temperature remains quite constant at about 28C except at the higher elevations. Some of the fish species are quite adaptable as they can be found in both alkaline and acidic environments. These species suffer no ill effects when moved from an acidic to an alkaline environment with little acclimatization. This adaptation is probably due to the periods of torrential rainfall, called the monsoon, which can quickly change the pH and temperature of the water. I discover this adaptive trait when I had to transfer the fish from the collection pail (pH 4) to the holding tanks (pH 8) and they survived. The lower parts of the rivers and some of their feeder streams are tidal meaning the salinity of the water changes with the tides. Some of the brackish water species could be found miles inland and sometimes in fresh water. I did not collect any brackish or marine species since they would be difficult to maintain.
In and around the city, a series of open drainage and sewer canals help flush the effluent from human habitation into the river and finally out to sea. There is no water treatment plant but each house has a septic tank that drains into the open sewer. Even in this polluted environment, I was able to collect Trichogaster pectoralis, Channa asiatica, Barbus binotatus, Poecilia reticulata (introduced species to control mosquitoes), an unknown goby species, and even a terrapin. While I was there, my cousin was able to net two blood parrot cichlid from the drain that I presume someone had dumped! Tilapia was introduced into a reservoir by the agriculture department for aquaculture. It seems that the people and the government have no regards of the consequence to the local aquatic fauna. The local fish stores stock mostly large South American cichlids and if any of these species escape or are released they would devastate the local fish fauna. The endemic species get no respect and some are fed to these large cichlids. The most common feeder species is Esomus danricus that is like a large danio with a really long pair of barbels extending past the anal fin. Small freshwater shrimps are also sold as feeder.
As the city is built on the lowlands, some of the streams are acidic because of the underlying peat (remnant of the peat swamp forest). In these streams I was able to collect Betta climacura, Rasbora kalochroma, Esomus danricus, Trichogaster trichopterus, Trichogaster leeri, Mastacembelus circumcinctus, Lepidocephalus thermalis, Barbus pentazona pentazona, Barbus binotatus, an unknown catfish, and a tortoise. The tannin leached from the leave litter causes the water to turn to the color of coffee. To catch the bettas, you have to scoop some of the leaf litter from the bottom of the stream with a net. Upon examining the contents you will see some bettas and if you are lucky you may also catch a loach or a catfish. To catch the rasboras and the gouramis, you will have to wait patiently for them to break the water surface and then quickly sweep your net across the general area of the ripple. Seining is impractical here due to the dense vegetation and the submerged tree roots. There are numerous aquatic and semi-aquatic plants but I did not collect any, as I would have problems bring them past Canadian Customs. Introduced aquatic plant species like the water lettuce and the water hyacinth grow like weeds and spread everywhere. One thing that you will have to watch for is the ubiquitous leech.
A short drive inland from the city would bring you to the foothills. Here the streams are clear, unpolluted, and swift running. The underlying limestone dictates the water chemistry of these streams which are hard and alkaline (much like Calgary’s water). This is also the source of the city’s water supply. The species collected here are Glyptothorax callopterus, Rasbora caudimaculata, Rasbora meinkeni, Rasbora argyrotaenia, Barbus rhomboocellatus, Barbus lateristriga, Barbus binotatus, Hemirhamphodon pogonognatus, Glaniopsis hanitschi, Bagarius bagarius, a Gastromyzon species, and an Homaloptera species. Each stream has its set of fish species with no two streams alike. Generally, there are no aquatic plants here as they would be swept away by the current. An interesting behavior was observed while collecting these species. When chasing the fish into a trap, most of them would swim towards and past the disturbance instead of away from it. One nice thing about these streams is that when you get tired of chasing fish, you could jump right in for a refreshing dip.
The fishes that I had collected came from small shallow streams. There are even more and bigger fishes in the bigger streams and rivers that are beyond my ability to sample. One way to find out what other species of fish are in the rivers is to visit the local fish market. Some of the food fishes that can be found for sale are large cyprinids and knife fishes. It is interesting to see that some of the aquarium fish species in Canada end up on the dinner tables in Asia. Another interesting observation is that although the Asian arowana is on the endangered species list, every local tropical fish store has a few for sale. The locals here are willing to pay an exorbitant price for a fine specimen because the fish is suppose to bring its owner good luck.
Bringing tropical fish out of Malaysia presents no problem. You do not need a permit to bring out your private collection. The tropical fish industry is well established in Kuching so there are no problem in obtaining a Styrofoam box and bagging your fish with oxygen. However, the airline charges about US$30 per kilogram (cargo price) for your box and so it could get quite expensive. The first time I tried to bring fish back to Canada, they wanted to charge me US$300 so I left the fish behind. I was so disappointed. The next time I brought a big cooler bag and hand carry it on to the plane with no problems at all. All the fish survive the thirty hours trip back to Calgary.
It is never boring when I go back home, as I seem to collect new species every time. However, I wonder how much longer the environment can withstand the onslaught of development. Everyday more of the rainforest is cut for timber, cleared for palm oil plantations, and swallowed up by urban sprawl. I guess it is not any different in Canada or anywhere else. Enjoy paradise while you can and don’t let the leeches suck!
REFERENCES:
Earl of Cranbrook & David S Edwards, 1994, A Tropical Rainforest, co-published by The Royal Geographical Society & Sun Tree Publishing.
Dr Herbert R. Axelrod, 1986, DrAxelrod’s Atlas of Freshwater Aquarium Fishes second edition, published by T.H.F.
Dr. J. D. Van Ramshorst, 1991, The Complete Aquarium Encyclopedia, published by Elsevier Publishing Projects.
Jorg Vierke, 1988, Bettas, Gouramis and other Anabantoides, published by T. F.H. ?