Items you will need
Pea gravel or rock substrate
Large river rocks
If you don't know how to take care of bluegills, you'll become their executioner rather than caretaker. Fortunately, taking care of the fish is easy. Knowing and practicing basic aquarium care is all that is required. Beyond that, setting up the tank so that it more closely mimics the bluegill's natural environment will move you from simply a caretaker to a good provider for the fish.
Buy an aquarium that's large enough for the amount of bluegills you will have, keeping in mind they can grow to 10 inches long each. Using the common one-inch-per-gallon rule, house two bluegills in a 25-gallon tank. The extra five gallons is added for the displacement caused by the pea gravel and other objects, plants and materials included in the tank.
Pour pea gravel or rock substrate onto the bottom of one part of the aquarium. Pack river mud onto the bottom of another part of the aquarium. Pour sand onto the bottom of the aquarium in another place in the aquarium and over the river mud. All substrates should roughly measure one inch up from the bottom.
Acquire both below-surface and floating plant life that's native to the bluegill's environment, and which they won't eat. Arrange the bottom plants into the river mud. Smooth the sand back over the place where the plants are buried in the river mud so that the river mud doesn't become a nuisance in the tank.
Build the river rocks on top of each other so that the bluegills have small coves and resting and hiding places. Arrange other river rocks so that the aquarium doesn't have a clear line of sight from one end to the other end.
Slowly fill the aquarium with water. Test the water from which the bluegill fish are coming from and compare it to the water in which you're putting them. Add ph balancer, as necessary, closely matching the ph balance in the aquarium to the water where the bluegill was before the aquarium.
Add the appropriate size water filter to the aquarium. Cover the aquarium with a lid.
Feed bluegills what they like to eat, such as native plant life, smaller native fish, insects and store-bought freshwater fish food. Don't overfeed them, especially if you don't have crawfish or other omnivorous bottom-dwellers in the tank.
Use an algae scraper or pad to clean the sides of the tank if the tank becomes too overrun with algae. Change the water by removing only 25 percent of the water at a time, as necessary. Always leave 75 percent of the water in the tank. Do not remove the live plants when changing the water.
Use a gravel vacuum to clean the debris from the rocks substrate, carefully avoiding the sand. Add bottom dwellers, such as catfish or crawfish, to clean the bottom of the tank.
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