Biotechnology and Bioinformatics (1+1)

6.2.4.2. Aquatic plant systems

Plants are not normally used for the primary biofilter in aquaculture systems. They do however provide a very good sink for the nitrates produced by a well functioning biofiltration system. The marriage of recirculating aquaculture systems and hydroponics are a good example of efficient use of resources.

· In addition to commercially valuable plants grown in hydroponics systems, aquatic plants such as hydrilla, cattails, water hyacinths and duck weed can be used to absorb nitrates and phosphorus from waste water.

· Unicellular plants (algae, diatoms etc.) are sometimes allowed to grow in the culture tanks.

· Some species such as tilapia are tolerant of poor water quality and can use the algae as food.

· Systems operated this way are sometimes called "green water" systems to distinguish them from the clear water systems that many species require.

· Green water systems can be a very cost effective way to culture certain species but they are not recommended for beginners to aquaculture.

· Management of these systems requires some experience and specific knowledge.