Southeast Asian Mangrove Estuary Biotope
Mangrove swamps are found throughout the world where freshwater rivers come into contact with the ocean. The result is a tidal region with varying salinity and water conditions. The tides affect some of the types of fish present in the estuary, although fish termed brackish water species remain no matter what the condition. The mangrove swamps can be found along the large river deltas, estuaries and coastal regions and due to the ever changing conditions the tree species that are able to survive are mangroves, not many other species are tolerant of these areas. The mangroves are evergreen and can cope with the salinity by producing roots that go deep into the mud to obtain what ever small amounts of oxygen are available.
The swamps are home to many amphibious species of fish like the mud skippers, this species will flee across the mud to escape from predators and they have a high level of intelligence.
Anablebs can also be found in the swamps, these fish are also known as four eyed fish. The common name comes from the fact that they possess double lobed eyes so that they can see above and below the water surface at the same time. They will leave the water on a regular basis as they like to perch on the tree roots and rocks.
Mangrove forests are under threat with being so close to the ocean as a lot of the land is being reclaimed for developing into tourist resorts etc.
The waters in these swamps are classed as hard 10 - 20 DH and as expected the pH is high, averaging 7.2 - 8.0. To recreate the brackish conditions the salinity should be set between 1.66 and 1.015.
Temperature of the tank needs to be set at 24°C minimum and 28°C maximum.
Setting up the tank
Coral sand makes an ideal substrate for the biotope, not only will it look attractive, it will also help to buffer the water to the correct PH. The mangrove roots can be created by using long branch like pieces of wood inserted into the substrate vertically. Good ventilation is a must as the brackish fish species are heavy eaters and will produce a lot of waste. A lot of keepers will only fill the tank halfway up with water and potted mangrove seedlings are then placed in the tank. The seedlings will then grow above the waterline allowing fish like the mud skippers to climb up to perch.
Plants for the tank
Due to the salinity of the water there are hardly any plants that will be tolerant of the conditions; one exception is the Java Fern. If mangrove seedlings are used be prepared for regular pruning to keep them low enough for the confines of the tank.
Fish for the tank
As mentioned mud skippers are my first choice for this biotope. They have some very unusual traits making them an excellent talking point. ON ability they have is to protrude their eyes out of the sockets to aid their vision; pulling them back in when normal vision is required.
Archer fish also show fine qualities when on the hunt for prey, they will shoot at insects with a spurt of water to dislodge them from leaves where they are ready to grab them from the water surface. If keeping these fish provide them with flies, crickets etc. for live food, but they will also accept flakes and pellets.
Scats can be added but these fish do grow quite large, be prepared to invest in a larger tank to home them. They are also herbivores; greedily eating any plants so do not add Java Fern with them as this plant is poisonous.
Puffers, Gobies, Glassfish and Celebes Rainbow fish also make for ideal inhabitants.
Source of information
Rhett A. Butler/mongabay.com