Table 3. Optimum feed particle size for catfish fry and
 fingerlings.
 Fish Size Particle Size
 (inches) (millimeters)
 < 0.5 0.42-0.60
 0.5-1.0 0.60-0.84
 1.0-1.5 0.84-1.19
 1.5-2.5 1.19-1.68
 2.5-4.0 1.68-2.38
 4.0-6.0 2.38-3.36
 > 6.0 3/16 inch pellet


 Raising Fingerlings

Pond Preparation and Pest Control
 Catfish can be grown to fingerling sizes, suitable for
marketing as seed stock, in a variety of rearing facilities
that include ponds, troughs, and raceways. In general,
many of the precautions and techniques of raising food-
sized fish in production ponds also apply to the methods
used in rearing fingerlings. To be successful, a producer
must maintain optimal water quality by practicing routine
procedures such as the following: (1) take care to exclude
all wild fish, predatory aquatic insects, tadpoles, and
other potentially noxious animals from rearing areas; (2)
monitor water chemistry frequently and take appropriate
remedial measures to control improper levels of dissolved
oxygen, pollutants, pH, sediments, etc.; (3) prevent
excessive growth of aquatic weeds and avoid overfeeding
and other sources of organic waste; (4) record water
temperature often and be especially cautious to avoid
heat-related stress; and (5) use appropriate drugs and
chemicals, following local regulations and suggested pro-
cedures, to contain or eliminate diseases and parasites on-
ly after conventional preventive measures have failed.
Diseases are a constant threat to cultivated catfish and
are of special concern to fingerling producers. Preven-
tion of serious diseases requires good management by
minimizing stressful conditions such as unfavorable en-
vironmental factors, improper handling, and poor nutri-
tion. Channel catfish virus disease (CCVD) poses a par-
ticular threat to fingerlings and requires special
consideration.
 Channel catfish virus inflicts fingerlings less than 6
 inches long and is highly contagious and usually fatal.
 Symptoms include hemorrhaging at the base of the fins
 and in the skin, distended abdomen filled with a clear,
 yellowish fluid, exophthalmia (pop-eye), pale gills, and
 erratic swimming behavior (these symptoms should not
 be considered as exclusive evidence for the disease).
 CCVD occurs primarily during hot weather when water
 temperatures exceed 68 oF (20 C), and develops more
 rapidly and results in greater losses as temperature in-
 creases. Very few effective treatments are available for


viral diseases of fishes, hence CCVD must be prevented
to avoid losses of entire stocks. A diagnostic laboratory
or fisheries specialist should be consulted to verify
suspected cases of the disease. The following measures
are imperative to prevent outbreaks of CCVD:

1. Prevent stress from low oxygen.
2. Do not move fingerlings when water temperature is
 over 85 F (29 o C). If fingerlings must be moved dur-
 ing the summer, they should be handled gently and
 as briefly as possible (however, do not move fish if
 CCVD is suspected).
 3. Prevent poor water quality from developing in rear-
 ing facilities by avoiding excessive buildups of am-
 monia, organic debris, and other toxic substances.
 4. Avoid large outbreaks of external parasites on
 fingerlings by using prophylactic measures. Do not
 treat for external parasites if CCVD is already
 present.
 5. Avoid very high stocking densities (i.e., greater than
 150,000 fry per acre).
 6. Do not use nets or other equipment that have been
 used in ponds or tanks where there has been a recent
 CCVD outbreak, without first disinfecting in
 Roccal (1,000 ppm for 5 minutes) or HTH (calcium
 hypochlorite) at 40 ppm for 5 minutes.

 Stocking Fry
 The optimal number of fry to stock depends on the
 management intensity, type of rearing facility, feeding
 schedules, water temperature, and other factors. Initial
 stocking density generally depends on the final size of
 fingerlings desired at harvest. Growth rate is determined
 by interactions between quantity of food consumed,
 stocking density, and water temperature, hence size of
 fingerlings at harvest may be highly variable (Table 4).

 Table 4. Estimated fingerling size after 120- to 150-
 day growing season under different stocking
 regimes. Optimal management techniques are
 required to attain these yields.
 Fry Stocking Density Average Length
 (fish per acre) (inches)
 10,000 7-10
 30,000 6-8
 53,000 5-7
 73,000 4-6
 95,000 3-5
 120,000 3-5
 140,000 3-4
 200,000 2-3
 300,000 1-2
 500,000 about 1