Danios, which are a group of small minnows native to the freshwater streams of Southeast Asia, are popular among freshwater aquarists. These hardy, active fish can thrive in relatively small fish tanks and come in a variety of species, sizes, fin types and colour morphs. The Japonica amano shrimp is a familiar tankmate to danios of all varieties, since it requires similar tank conditions and is equally hardy. In general, danios and amano shrimp do well together in captivity.
Set up your aquarium by filling a 29-gallon tank with water, then spreading an inch-thick layer of gravel substrate on the bottom of the tank. Plant hardy freshwater plants, such as Amazon sword and Java fern, throughout the tank. The plants should be in small clumps that provide hiding places for the fish and shrimp, but also allow for spacious swimming room. Add the manufacturer's recommended quantity of water conditioner to eliminate chlorine and chloramines.
Install the hood, thermometer and filter according to the manufacturer's directions. Danios and amano shrimp will both do best at a stable temperature of 64 to 75 ° F. Because most homes stay within this temperature range, you are not likely to need a heater.
Introduce three to five amano shrimp to the aquarium. Feed them sparingly once per day for two weeks, checking your nitrate, nitrite and ammonia levels daily to ensure that nitrifying bacteria are populating the aquarium. Change the water as necessary if levels of nitrate spike above 20 parts per million, or if your test strips reveal detectable nitrite or ammonia. The pH of the water should be 6.0 to 8.0.
Determine how many danios you will introduce to your tank. The number of fish that the tank can accommodate will depend upon the species in your care and the number of amano shrimp in your care. Using the classic one-inch-per-gallon rule, five adult amano shrimp would occupy ten gallons of water. This would leave room for nine adult zebra danios, nine adult leopard danios, or five adult giant danios. Remember that danios thrive in schools of five or more.
Introduce danios to your aquarium after the aquarium has "cycled"--that is, after your test strips reveal stable nitrate levels below 20 ppm and consistently undetectable levels of nitrite and ammonia. In general, it is best to introduce two to five fish per week, so that the aquarium's ecosystem is able to accommodate the extra waste load with few major fluctuations in water chemistry.
Check nitrate, nitrite, ammonia and pH levels weekly. Perform water changes as necessary to ensure consistent readings that remain well within the needs of both danios and amano shrimp.
Feed your danios and amano shrimp daily, offering small quantities of food during each feeding. The fish and shrimp should be able to consume an entire feeding's worth of flakes within one minute. Understand that too much food can elevate levels of nitrates and ammonia within the water.
Use caution when handling electric aquarium equipment, particularly if your hands are wet.