Colisa species: Indian gouramis

Similarities among the Colisa species, which include the Dwarf Gourami (Colisa lalia) are strong enough to consider them all together. In addition, some of the species' individual  characters have been blurred in aquarium strains, I'm convinced, by hybridizing, consciously or unconsciously.
 
Inconsistencies in early descriptive naming of Colisa on the part of two giants of early ichthyology, Baron Georges Cuvier (in 1831) and Francis Buchanan-Hamilton (in 1822), have recently resulted in a switch: either one is meant to give Colisa Hamilton's unfamiliar name, Polyacanthus, which seems to have precedence following the international rules of biological nomenclature, according to the California Academy of Sciences Catalog of Fishes entry, or to giveTrichogaster for Colisa and  substitute the unfamiliar Trichopodus for Trichogaster, according to a 2005 article by Ingo Schindler  in Der Macropode, which does give the flavor of the confusion: cripes! It seems that like many of their generation, those old-school biologists didn't designate a type specimen for Colisa. A quibble, if you ask me. To add to the mess, Polyacanthus is masculine, so now Colisa lalia becomes Polyacanthus lalius. In February 2010 an application for waiver of the strict rules, often made in such cases where an "incorrect" name has become firmly established,  was made to the International Commission on Zoological Nomenclature. In the interim I'm sticking with Colisa till the dust settles.
 
Maintaining these threadfin gouramis at steaming tropical heat approached 80^o year round keeps them constantly in display coloration but shortens their fairly brief lifespans. A "winter" rest of a few months at temperatures in the low 70s results in sturdier fish. 
 
Colisa chuna (Honey Gourami). It's increasingly hard to find the natural C. chuna from northern India (Assam) and Bangladesh; it is replaced at your LFS by its hybrid with the Dwarf Gourami, called a "Honey Gourami" or by some other fanciful "uncommon" name. A "Honey" Gourami, mis-identified as a "variety" of Dwarf Gourami, made the cover of Aquarium Fish for Feb. 1994. The genuine C. chuna, is a slightly delicate little beauty who will appear drab at the fish store but whose males color up to a russet color when they've settled into a planted aquarium; they get redder and display an intense black throat patch at breeding time. The females, constantly courted by the male, are convicted of the capital sin of being less colorful. The females are different enough that Hamilton-Buchanan described them as a separate species in 1822, Colisa sota; the recently-compounded confusion of names remains to this day.
 
C. chuna links. Colisa chuna at FishBase. Brian Carson identifies "The 'true' Honey Gourami, Colisa chuna" and describes breeding and raising fry in an article originally written for the Greater Pittsburgh Aquarium Societ but archived by the Oklahoma Aquarium Association; he notes that the false Honey Gourami at your LFS is probably a color form of C. labiosa. 
The  brief illustrated entry on C. chuna at Aquaworld shows the fish in its pale stressed coloration, but Dr Peter Gruendler has posted four excellent photos of his C. chuna spawning in a low-tech tank with plenty of floating plants, where traces of ammonia and even a little nitrite didn't seem to make a difference, at pH 7.4. The watchful male took his brood in his mouth and shifted them from leaf to leaf.
 
Newly-free-swimming gourami fry are all extremely small, so it's not easy to know what to feed them. A useful 1998 Live-Food Digest thread rating green water, infusoria,microworms and the biofilm on plants, even artificial plankton, for feeding C. chuna fry is  archived at The Krib. Follow the thread through to get all the good information and the excellent highly-informed geek flavor.
 
Colisa labiosa (Thick-lipped gourami). Colisa labiosa and a very closely-related species, C. fasciata, have been blurred together into hybrids for the hobby market, "probably" I thought in 2002 but Aqualognews, issue 15 (undated)  confirms my suspicion. C. fasciata is sometimes quite earnestly called the "Giant Dwarf Gourami," so if you were to see some juveniles at the fish store, I guess you might ask for "a small Giant Dwarf Gourami."
 
Though you'd be more likely to be seeing the true Giant Goramy, Osphronemus goramy, featured on "Iron Chef," this food fish has turned up in the aquarium trade from time to time and could be given to a naive friend as a cruel practical joke.
 
A selected naturally-occuring variant of either the real C. labiosa or its hybrid form, is the good-looking "Sunset Gourami." That fish is often confused in turn with the "Flame Gourami," a name that should properly identify a selected de-striped form of C. lalia. All utterly confusing, eh. Casually mis-identifying photo captions in the TFH books on Anabantids have rendered us even more confused. The "Sunset Gourami" is slightly smaller than typical wild C. labiosa individuals. It might be a little drab in the retail store. At home it's a warm pinky golden brown with an orange-gold edge to the dorsal and anal fins. The wild labiosa type is striped with pale blue and comes from the heart of "Colisa country:" northern India, Bangladesh and Burma.
 
In both kinds, females are less intensely colored and plumper in form, and the rear corner of their dorsal fin is more rounded than it is on the males.
 
Spawning activity of C. labiosa was well described by Iggy Tavares in F.A.M.A., Feb. 1999, pp 42ff. He noted typical Colisa mating action: the male building a bubblenest in one corner of a planted (with silk plants) aquarium while the female filled with eggs. The male courted the female, who took refuge among the artificial plants. When she was ready, she came to him — a good point for Colisa marriage brokers to remember — under the nest. There they did their rolling embrace; he spat the eggs up into the nest, then chased her off when she was spent. The fry hatched after 30 hours and could be seen hanging from the nest, while the male tended to any stragglers.
 
C. labiosa links. Colisa labiosa at FishBase.
 
Colisa lalia (Dwarf Gourami). This astonishingly handsome little fish is so common in Northern India and Bangladesh that it's been introduced to areas where it wasn't native, to handle malaria mosquitos. Escapes from fish farming have established Dwarf Gouramis in Singapore and the nearby southern end of the Malay peninsula, and even in the Baram River of Kalimantan (Borneo), where you can be sure Mother Nature never placed it.
 
In northern India, C. lalia take from 8 to 12 months to mature. Larval fish from the summer spawnings overwinter and mature by the peak temperatures of May and June, when they start breeding repeatedly til the cooling monsoon rains of July and August dampen their ardor. Take this cue and, if you can locate a female, you can encourage spawning in the aquarium by slowly raising water temperatures to about 82^oF. Wiljo Jonsson has a series of truly outstanding close-focus pix showing Dwarf Gouramis spawning at his site, among the "Akvariefiskar" at his site.
 
Omnivore diet. We think of gouramis as omnivores, eating some green plant material to supplement their diet. An inspection of the guts of C. lalia in Singapore fishponds revealed these contents: fauna (in descending order of volume): cladocerans (e.g. daphnids),copepods, ostracods ("seed shrimp;" this is an unexpected food item!), rotifers, insects, protozoa; flora (in descending order of volume):cyanobacteria (yes! another surprise eh?), green algae, diatoms, euglenoids ("green water" protists). I was surprised not to see molluscs (snails). With a menu like this, you shouldn't be surprised that Dwarf Gouramis spend all day picking over the plant surfaces in a densely-planted aquarium.
 
For their size, male Dwarf Gouramis can be unexpectedly aggressive, especially when they're in bubble-nesting mood. Ordinarily there's room for only one fully-colored dominant male, even in a roomy planted tank. Other males will look pale and harassed. Mixing color varieties is unlikely to have an effect on aggressive behavior. A pair of females, though, can share the stress of the male's attentions. Their natural rhythm in native waters also suggests that, if territorial pre-spawning behavior is making life too rugged for your Dwarf Gourami's tankmates, you might try lowering the temperature a bit. Dwarf Gouramis like to incorporate shreds of floating plants into their bubble nest. A couple of strands of Cabomba or Myriophyllum will do just fine.
 
 
Dwarf Gouramis arrived early in American aquaria. They were mentioned in a 1908 book by Otto Eggeling and Frederick Ehrenberg, The Freshwater Aquarium and Its Inhabitants. Eggeling imported some tropical fish directly from Calcutta. That's gourami country. Was the Dwarf Gourami among them?
 
A good male Dwarf Gourami will show clean uninterrupted diagonal scarlet stripes against metallic turquoise blue; I've never seen the point of eliminating the stripes through selective breeding to create the "Turquoise Dwarf Gourami," which invariably presents creases and dings in its metalflake coat! Moving in the other direction, selective breeding has eliminated the blue stripes altogether, to produce the "Flame Gourami." "Sunset Gourami" however, was the name applied to these red C. lalia varieties by Atsushi Sakurai, in Aquarium Fish of the World, Singapore, ca. 1990. He says these were first bred in Singapore in 1980. 
 
The traditional Dwarf Gourami holds a special spot in my heart because, when I was about eleven, it was the first egg-laying tropical fish to spawn for me, in a 5-gallon aquarium set on the toilet tank in a bathroom that I shared with my brothers. The memory is a high point of our childhoods.
 
Commercial mass production. Though the Dwarf Gourami used to be recommended as a good beginner's fish, I couldn't recommend it whole-heartedly now to anyone. Dwarf Gouramis have weakened in the last forty years. Now they come to your LFS riddled with the tell-tale lumps in their musculature of encysted metacercariae formed by dormant parasitic trematodes, and chances are better than one-in-five carrying the incurable and fatal "Dwarf Gourami iridovirus (DGIV)" to infect your other Anabantoids. Tropical Fish Hobbyist, not traditionally the most skeptical critic of the aquarium trade, now says in their species profile of Trichogaster (Colisa) chuna "There have recently been quite a lot of health problems with dyed, hormone-treated, and virus-carrying gouramis commercially bred in the Far East, so careful selection and mandatory quarantine are required when purchasing these fish." And Dwarf Gouramis are martyrs to camallanus, an insidious intestinal nematode.
 
Natural females are larger than males, plumper, more silvery. The females are often held back from the retail market now, or else they come to you "juiced" full of methyl testosterone to give them spurious butched-up male color. Such hormone-treated individuals may prove to be sterile, if they can be induced to spawn. When you call for females at your LFS, you'll likely be told "we get no call for them." You may have more luck at your unselective low-end chain store, where the untreated females can slip through. Buy three if you need one, and quarantine them carefully, with prophylactic treatments for skin and gill flukes, ich, and possibly for intestinal nematodes. All in all, you have a seriously diminished chance of witnessing the beautiful spawning ritual that impressed me so many years ago.
 
Singapore is the world's center for mass-produced gouramis, among many other hobby fish. There they are raised in concrete-bottomed outdoor ponds protected by netting. Chicken manure fuels a rich soup of green water algae, which can drive the pH as high as 10.3 during peak hours of photosynthesis! You could get a clear picture of the fish-farm management techniques recommended for pond-raising gourami s— and other fish — in Singapore at http://www.dbs.nus.edu.sg/fish or http://www.science.nus.edu.sg/~webdbs/fish/gourami/gourami.html, both links now scrubbed from the semi-official National University site, which made the following recommendations, circa 1998: "Another technique that could be employed is the use of hormones and/or chromosome manipulations to produce all male generations of fish, as is done with tilapia. This would increase the yield of the more valuable male fish and reduce the number of the less-valuable females. Finally a more systematic approach should be taken to producing hybrids between the different color varieties of dwarf gourami and between the different gourami species. This would create new and more profitable varieties of fish in the future." These repellant techniques are actually commonplace. But if you were to ask anyone in the Southeast Asian wholesale export trade, these practices would be flatly denied as unfounded rumors.
 
Tank-raised? So now, if you were planning to establish a clean, disease-free, tank-raised strain of carefully-selected fishes of the natural type, I'd pay a premium for a pair of those. I wonder how many other fishkeepers would too. So in the meanwhile, maybe your best source of Dwarf Gouramis could be the auction of a local fish club: another reason to join, eh?
 
Mark Denaro, of Anubias Design, imports wild C. lalia, offered at reasonable prices; Mark is reachable through a dedicated yahoo group. Though the fish are not expensive, you'd want to get together with some other aquarists to assemble a group order, because it's the shipping that raises the price.
 
 
Colisa lalia links.  There are three descriptions of spawning Dwarf Gouramis at The Krib. 
 
Colisa lalia at FishBase.