Southeast Asian River Biotope Aquarium
South East Asia covers generally mainland Asia plus the islands of Sumatra, Borneo and Java. In earths long past these were all joined together with a large river system running through them all. This area is rainforest where the land water will move down to lots of tributaries. In the rivers there is virtually no current, a very slow moving environment with lots of dense and decaying vegetation. Bamboos and ferns are above and below the waterline, the natural substrate and rocks being a deep red coloration as there is a strong concentration of Iron in these waters but the overall mineral content is very low.
Due to the rotting vegetable matter the water is acidic; a pH of 6.0-6.5 should be maintained in your biotope. Hardness should be between 2-8 DH and the water temp in this area is on average between 26-29°C, once again these should be duplicated in the biotope.
Salt can also be present in some areas, admittedly in low concentrations, but if added to the tank in small quantities it will be beneficial to the fish without harming the plants. As the natural are comprises of various river tributaries, there are many places where the depth of the water can be very shallow, this means that when selecting your tank depth is not a key issue.
Setting up the Tank
For the purposes of this biotope length in the tank is more crucial than the depth. For a pleasing visual display and to recreate the shallow river scene required, I would suggest a tank that is 48 inches in length, 12 inches width, and 15 inches high. This will give the illusion of a long shallow river, but if space is at a minimum then a 36” tank will suffice but remember that some of the fish that will be included in this set up will grow to quite a large size. The substrate needs to replicate the deep Iron red of the natural habitat so the obvious choice there is some nice rich red laterite, this will also be of great benefit to the plant life. On top of this add some fine red gravel or sand, even separating areas of just sand or gravel will enhance the look. Another option is to use the Seachem Fluorite; this is red clay gravel that also acts as a great plant growing medium. Add some bogwood to replicate tree roots, not too much though as this can ruin the effect. Scatter some small pebbles and rocks in a random fashion but make sure they are inert as the water is acidic and they could react with it if not. The substrate should be slightly higher at the back of the tank so as to give the impression of a sloping bank plus any detritus will fall to the front of the tank making it easier to siphon out. This is all the hard scaping that is required, now we need to look at the plants to be added.
Plants for the biotope
Suggested plants for this set up include Cryptocoryne Wendii, Cryptocoryne Nevilli, and Hygrophila Polysperma. Some keepers will add Vallisneria to this set up to give a good mid ground effect with the long strands of leaves floating upwards to the water surface but I find these tend to grow better in neutral to slightly alkaline conditions. This doesn’t mean that they will not grow in an acidic environment so try a couple of plants if you wish just to see how they get on.
With the crypts it might be better to add them after the tank has been running for 2-3 months as they do not like new tank set ups. They will often suffer from crypt meltdown where all of the leaves will die off but these should re grow if left to their own devices.
Onion plants will also be suitable but remember to leave the crown of the bulb showing above the substrate. Bamboo plants are also a good choice for this biotope and if the tank is open topped then allowing some shoots to grow above the water surface can make a very good effect.
Most loaches, Barbs, Danios, Red tail sharks, Bala sharks, and small Asian catfish are more than suitable for this biotope. Always check that the size of the tank is right to suit the adult size of the fish you are adding or be prepared to move the adults to a larger tank in the future. Bala sharks and clown loaches will definitely out grow a three or four foot tank so research before buying. I have seen this biotope set up with just a shoal of green tiger barbs and the effect was stunning.
Lighting for the tank
Add sufficient lighting to encourage the plant growth but do not add excessive lighting. This will lessen the natural effect you are trying to create, if necessary it might be advisable to add a CO2 system to make up for the lighting shortfall but let the plants settle in before deciding whether to pay out for this additional equipment.
As with any tank set up the filtration must be able to cope with the livestock that is being added but what you do not want is a fast current flowing through the tank, this will also spoil the overall effect you are trying to create. If you are running an external filter then add a spray bar to disperse the current from the outlet pipe, it may be even necessary to have it pointing towards the back glass to reduce the current even further. If you are using an internal filter it is even possible to buy spray bars for some of the more popular models. Failing that adding a wide outlet nozzle will dampen the water flow.
It may be necessary to add extra oxygen via an air line due to the lack of current but if this is the case a steady stream of bubbles sited in the corner of the tank should not be too conspicuous.
Additional sources of information
mongabay, aquarticles, wetwebmedia