Macropodus opercularis fish better known by the name of Paradise Fish were one of the first freshwater ornamental fish are kept in the early days of the aquarium in Europe. The paradise fish or paradise gouramis, are small freshwater labyrinth fish found in ditches and paddy fields in East Asia, ranging from the Korean Peninsula to Northern Vietnam.
As the first ornamental fishes available to western aquarium keepers, Paradise Gouramis have been imported to Europe as early as the 1800s. These small fish (adults are typically about 10 cm (4")) are ideal lone inhabitants of aquariums. The paradise fish is one of the more aggressive members of its family, by being more aggressive than the blue gourami. Yet they are far less aggressive than the rarely kept Combtail.
Generally, Paradise Fish behaviour are fairly combative, harassing and attacking each other as well as potentially killing small fish. In the wild, they are predators, eating insects, invertebrates and small fish. The popularity of this species has waned in recent decades as much more colorful (and often, less pugnacious) species of gouramis have become widely available to hobbyists. However the privileges of paradise fish, this species is one of the few fish that can change its color (lighter or darker) in response to stimuli.
Other existing features of this fish maybe because paradise gouramis also tolerant of virtually any water conditions, surviving in cool and warm waters alike. They can be kept in outdoor ponds, or even the simplest of unheated aquariums. They will accept virtually any food, but should be given a reasonably high-protein diet (as opposed to vegetable-based foods of the sort sold for goldfish.)
Paradise fish are bubble nest builders. As is typical of most bettas and gouramis, Paradise fish spawning involves a male building a bubble nest with floating mat of saliva-coated air bubbles, often incorporating plant matter and then attracting a female to it.
Breeding can be triggered by raising the temperature, although have found that they will breed in winter with no apparent change in environmental conditions. When the female is ready to mate she will approach the male and turn on her side. The male wraps his body around hers, and she releases eggs at the same time that he releases sperm. The eggs are lighter than water and float up into the nest. The male gathers the fertilized eggs after each embrace, spitting them up into the bubble nest.
After spawning, the male has no further use for the female and may violently attack her (and any other fish that approaches the nest.) Once the fry hatch and have begun to swim freely, the male is best removed and the fry raised on infusoria or newly hatched brine shrimp.
In Taiwan the native populations of Paradise Fish have been reduced to low levels by pollution in the rivers, and now it is listed in Taiwan as a threatened species. The Aedes mosquito (Aedes aegypti) is breeding in the absence of one of its main predators, and dengue fever is threatening the Human population.
