Many forms of bivalve mollusks can create pearls including clams, abalone and mussels, but the majority are produced by oysters. Prior to setting up your aquarium for pearl oysters, research the type of oysters you want to raise and establish a habitat that most closely matches their natural environment. You can purchase oysters who have been seeded with a pearl or other irritant. The oyster secretes a mineral substance called nacre, which coats the foreign object and creates the pearl.
Sizing Up Your Aquarium
Sensitive to ammonia from waste products, oysters require a well-filtered environment and don't tolerate overcrowding well. A 20-gallon aquarium generally accommodates up to 20 adult oysters comfortably. When populating your aquarium, add only a few oysters the first week, along with a bacterial water culture. The bacterial culture will help establish healthy bacteria, which convert harmful waste products into harmless nitrites and nitrates. Once your bacteria is well-established, you can add the remainder of your oysters.
Filtering for Filter Feeders
Use a combination of filtration for your oyster aquarium. Install an under gravel filter, which consists of plastic plates beneath the substrate, with rigid vertical tubes at each end. Air stones installed in each tube, attached to an air pump, provide circulation and oxygenation, which allow your bacteria to flourish and convert ammonia. Add canister filter or back filter, which removes particulate matter and helps keep your tank water clear.
Engineering Your Environment
Place a substrate of crushed oyster shell, crushed coral or dolomite over your under gravel filter, rinsing thoroughly prior to installing. Add water to the aquarium, pouring it over a plastic lid or dish to prevent the water from disturbing your substrate. Use a commercial chlorine remover and add aquarium salt to achieve the proper specific gravity for your oysters. Most live comfortably in 14 to 21 grams of salt per liter of water, but check with your oyster vendor to determine your oysters' exact needs. Water at room temperature normally suffices, and heaters rarely are needed.
Initially, your water may become cloudy and have a slight ammonia smell. As the bacteria in your tank becomes established, the water will clear up and the odor will diminish. During this period, do not overpopulate your tank. Once your habitat is established, replace 25 percent of your tank water on a monthly basis. Doing so removes nitrates, proteins and excess food products that can promote algae growth, while replenishing salts and other minerals. Prepare the replacement water the day before performing the change and allow it to sit overnight to achieve room temperature.
Feed your oysters a commercially available invertebrate diet, which you can purchase at your local pet store. Feed your oysters three times each week, turning off your filtration system for 30 minutes at each feeding. Since oysters are filter feeders, disabling your filtration system will allow the oysters to obtain nutrients from the water before the filter has a chance to remove them.