Fish Farms

The arrows in this selection show that the water flows

• through the ponds and out into the river.
• in a complete, closed loop throughout the farm.
• from the fish tanks directly into the aeration pond.
• from the filter tank directly back into the fish tanks.

Two separate ponds are needed on this fish farm, so that

• fish have two areas in which to swim.
• there are two sources of fresh intake water.
• each pond can perform a different function.
• there are different habitats in which plants can grow.

The purpose of the "shallow filtration pond" is to

• grow water plants.
• mix oxygen into the water.
• drain solid waste from the water.
• remove chemicals from the water.

A pump is necessary in the fish farm to make the

• clean water flows faster.

• fish move from tank to tank.

• oxygen bubbles move around.

• water move up into the fish tanks.

The effective operation of all components of the fish farm ensures that

• solid waste is used to feed plants.

• water in the filtration pond has sufficient oxygen.

• new water is added to the system at several points.

• the fish have a continuous supply of aerated water.

The fish farm in this selection is "eco-friendly" because

• the farm reuses cleaned water.
• the farm uses organic fish food.
• gravity is the only source of power.
• a blower mixes oxygen into the water.