Clown loaches, Chromobotia macracantha, are attractive fish and thrive in Discus … Discus (Fish) Tank Conditions. Discus fish are more suited to darkness and demand a dim lighting usually for around 10-12 hours a day. For Discus fry, high temperature helps to raise metabolism and ensures proper growth. Discus fish is extremely popular across the world and many people have managed to accustom them to different conditions. The discus fishes are most often shy and therefore you need to place them with dither fishes in their surrounding as it helps them to understand that they are not in any danger and can live stress free. Ideal pH. As a discus keeper, you must be able to find out why are your discus fish tilting and laying flat on the sideways in the tank. Keeping this warmer temperature will reduce the chance of illness and deaths, it can be maintained using a good quality heater. The discus fish can grow quite large, in some cases 10 inches, therefore, the aquarium size should be sufficient to accommodate not only your discus but also any suitable tank mates. It’s always important to monitor your aquarium water and fishes since any change in the behavior of a fish can be a sign disease in the tank. The dimensions should be 40” x 16” x 18”. Discus Fish Laying Down on its Sides. If, however, you are not keeping small fish and are happy to give Angels a go, then choose tank-bred specimens over wild fish as this lessens the potential for importing parasites. Discus fish are very specific about their tank requirements and one of these requirements include tank lighting. If the fish are fully grown, the tank must be as big as 80 gallons. Clown loaches. So, how exactly do discus fish prefer the lighting in their aquarium? Group of 10 companion discus with plants will require a 105-gallon tank fully grown discus. Rearing group of discus will need a 50 gallon tank for 10 fish. If the tank is not large enough this could create an environment that creates stress and lead to bad water conditions if water changes are not done frequently. But as the discus fry grow up, the tank should be kept at 82-84°F, otherwise, it will shorten your Discus’s life span by several years. While I have clearly defined the ideal conditions you require to set up a discus fish tank, it is possible that the fish you bought are used to different conditions. Discus fish and their suitable tank mates. These fish require higher temperatures than most fish 82-88°F. Amazonian water is soft and slightly acidic, with a pH between 6 and 7.