These facilities have the resources to build large enough tanks to house the sharks. Sand sharks can be kept in a tank with other large fish. The sharks are usually fed three to four times a week to discourage them from eating tank mates. For the most part this works well, although, every so often some of the fish seem to disappear. If a particular fish lives on a coral reef, try to incorporate that into the grand scheme of the aquarium. Stress can be minimized by providing ample opportunities for fish to act normally. Lastly try to avoid overcrowding the tank. This is another common problem that can be easily avoided. A general rule of thumb is one small fish per every ten gallons of water. They are simple bubble coral, pearl bubble coral and grape bubble coral. They are all cared for in the same way, so they will be referred to as bubble coral throughout the rest of the article. One of the most important things to know about your coral is how to space them when you add them to the tank. When cleaning the tank, you will need remove of stir the gravel to remove sediment that could possibly change the chemical make up of the tank. Use caution when cleaning an acrylic tank and be sure that the cleaning supplies being used will not harm the tank in any way. The best thing to use to remove algae is phosphate drops. Guppies mature quickly and usually only grow to be about one and a half to two inches long. There small bodies and feathery fan like tails add a lot of interest to the tank. They are just fun to watch. As with any type of aquarium, there are three basic components to caring for the fish. Diet is very important. Change about a third of the water in the aquarium at a time, because this type of change will cause the least amount of disturbance to the fish and other inhabitants. This will need to be done every two to three weeks. Use either a bucket or a siphon to remove the water from the tank. Try to remove any loose or floating debris at this time.