Interdependent Ecological Balance—Small World of Endless Life Top


No. 12
Mosquitofish (Gambusia affinis)

Interdependent Ecological Balance—Small World of Endless Life

Reprinted/Taiwan Digital archives


“Ecosystem” means all the organisms within a certain area and their living environment combined. In an ecosystem‚ the sun’s energy is continually passed between various organisms through the food chain. Taking this small pond as an example‚ the organisms of an ecosystem can be roughly divided into three types:

Producers: Green plants and algae are the main producers. Through the process of photosynthesis‚ they absorb the sun’s energy and store it within their bodies. The algae in a pond are producers.

Consumers: Most consumers are animals. Animals that eat producers are called primary consumers (such as zooplankton); animals that eat primary consumers (like Amano shrimp or guppies) or called secondary consumers‚ and so on for other animals. The highest level consumer in this small pond is the Paradise fish.

Decomposer: The dead bodies and bodily waste of organisms return to nature with the help of decomposers‚ where they are used by other creatures. Most decomposers are microorganisms.

If the relationships between the organisms in an ecosystem achieves a stable balance the ecosystem can continue far into the future; however‚ if this balance is upset the ecosystem can collapse overnight. Maintaining an ecosystem’s stability‚ even if just a small pond‚ needs constant attention and strict monitoring so‚ whatever you do‚ don’t release turtles‚ goldfish and other non-native creatures into the local pond!

The most eye-catching character in Taiwanese ponds

Mosquitofish (Gambusia affinis)

In ponds in Taiwan shoals of mosquitofish can often be seen. Do you know how this fish crossed the ocean and settled in Taiwan?

The Mosquitofish is native to the Americas‚ and is distributed across the eastern US‚ Mexico and Cuba. Their ability to survive in highly polluted water and liking for mosquito larvae as food led to them being introduced to Taiwan in 1913‚ when they were released into irrigation channels and began their anti-malaria mission. Today‚ they have spread across Taiwan.


Mosquitofish (Gambusia affinis)
(Image source: Biodiversity Research Center‚ Academia Sinica)

Paradise fish (Macropodus opercularis)

It is said in Taiwan that a family that keeps paradise fish will be a disharmonious one. Actually‚ the Paradise fish is much less aggressive than the Thai fighting fish seen in aquariums. They also have a wonderful way of reproducing! When the male fish is mature they blow resilient bubbles next to water weed at the surface and make a “bubble nest.” When courting‚ the male will carefully encircle the female and gently squeeze her belly to induce egg laying. After the eggs are fertilized‚ the male picks up the eggs one at a time and deposits them in the bubble nest.

The male then attentively stands guard at the side of the nest‚ occasionally blowing new bubbles to main the structural stability of the nest and driving off any other fish that come too close. After two or three days the eggs hatch‚ but the young don’t yet have the ability to swim and rely on the yolk sack on their bellies for nourishment. As soon as they can swim they eat plankton. The daddy Paradise fish will continue to take care of the young until they can live independently.

Apart from blowing bubbles to make a nest‚ paradise fish can often be seen sticking their mouths out of the water; what are they doing? They are actually breathing! The Paradise fish is a Suborder Anabantoidei fish and their gill arch has‚ through the process of specialization‚ developed sack shaped mucosal tissue like a maze‚ called a labyrinth organ. This organ allows the fish to breathe air directly at the surface‚ so the Paradise fish is able to survive in water with very low oxygen content in which other fish can’t live. Next time you see a paradise fish taking a gulp of air at the surface don’t be surprised!


Paradise fish (Macropodus opercularis)
(Image source: Tzeng Chyng-Shyan)