Floating cages can hold catfish forgrowout where tradition-
al pond culture is not practiced.

a great deal of stress and may succumb to diseases and
parasites more easily if they are crowded; (2) treatments
for diseases are more difficult to administer; (3) feeding
management of caged fish must be relatively intense; and
(4) poaching becomes easier.
 Cages are made of vinyl-coated wire, polyethylene,
nylon, or other corrosion-resistant mesh on PVC, wood,
or metal frames and are suspended freely in the water
column. Many cage designs and sizes have been used, but
most are 1-2 cubic yards (0.8-1.5 cu. meters) and made
of 1/2 inch or larger mesh. Cages may be either cylindrical
or rectangular, but the design and placement in the water
must allow for a depth of at least 3 feet of water in the
cage. Tops of cages are usually made of a solid opaque
material, such as plywood or aluminum sheeting, and
must have a feeding ring. The feeding ring is an enclosed
cylinder of wood, mesh ('/s inch), or other suitable
material attached to the top of the cage and extending
about 4 inches above the top and 12-16 inches beneath
the water surface. Producers generally give caged fish
floating feeds, which should be placed within the feeding
ring to insure that food does not pass outside of the cage.
Cages may be attached to metal or wooden stakes or piers
in an open body of water, or they can be floated using
styrofoam pontoons, plastic bottles, or other bouyant
materials. They should be floated with the lid about 3-6
inches above the water and with at least 12-36 inches be-
tween the cage and the bottom of the pond or lake, so
that fish wastes are adequately dispersed. Cages should
be placed at least 10 feet apart. It is important to fre-
quently check caged fish for signs of stress, infections,
and parasites and to treat them accordingly if necessary.
Clean cages periodically to remove growths of filamen-
tous algae.

 Water Quality

 As with hatching fry, the rearing of food-sized fish
depends vitally on good water quality. The most impor-


tant water quality characteristics include dissolved ox-
ygen, temperature, pH, total alkalinity, and total hard-
ness. Standard instruments and kits for measuring these
parameters are available through commercial suppliers.
Water quality should be checked once per day around
sunrise.
 The pH of water to be used for catfish culture should
be between 6.5 and 8.5. Water that is not in this range
can be treated with effective buffering compounds, such
as agricultural lime to increase pH, and hydrochloric acid
or aluminum sulfate to decrease pH. If the total alkalinity
or total hardness of pond water is below 20 mg/liter add
lime during the late fall or early winter. Ponds in Florida
near limestone or similar sediments ordinarily should re-
quire few corrections for total alkalinity and hardness.
 Growth of catfish is greatest at water temperatures of
80 -85 F (27 -29 o C) and is least at temperatures below
60 oF (16 C). This translates into a maximum growing
season of 200 or more days per year in many areas of
Florida. Catfish can tolerate the normal low water
temperatures in the state, but their survival, growth, and
food conversion may be jeopardized by combinations of
high water temperature, low dissolved oxygen, high stock-
ing density, disease, and other chemical and biological
interactions. Consequently, Florida farmers should make
a special effort to carefully monitor summer water quality
and take remedial measures if poor water conditions
develop that may adversely affect fish health.
 Dissolved oxygen concentrations should be measured
frequently and maintained above 4-5 ppm. Oxygen levels
fluctuate widely and may be influenced by factors such
as algal blooms and plant growth, wind, cloud cover,
amount of decaying organic sediments, and temperature.
Oxygen in the water is lowest at sunrise and can be low
on overcast or rainy days, due to respiration by algae,
bacteria, fish, and other organisms, and the lack of ox-
ygen production by algae and aquatic plants. Algae are
the main producers and users of oxygen. Moderate wind
action helps to aerate water near the surface, but strong
winds may stir up oxygen-deficient sediments and cause
low oxygen levels throughout the water. To reduce stress
and physical harm to fish from low oxygen, a successful
producer must measure oxygen often, take preventive
measures, and have emergency aeration equipment
available. A variety of aeration devices are on the market
or can be built with relative ease, ranging from tractor-
propelled paddlewheel aerators to floating, electrically-
powered models. Pond owners can further reduce prob-
lems associated with low oxygen by aerating incoming
water if necessary and maintaining a proper algal bloom
by not overfeeding the fish.
 Water should never contain pollutants or toxicants.
Certain metals, pesticides, and other compounds can be
extremely toxic to fish. Galvanized equipment may release
enough zinc to kill catfish, and copper toxicity may result