The market for channel catfish in the United States is well developed.
Once considered a product of interest only in the southern states, catfish can now be found in restaurants and on menus in grocery stores throughout the nation and
is seen by consumers as being a healthy choice food.
Channel catfish brood stock are easy to maintain in pond culture,
and spawning efficiency is reasonably good without any special manipulation of environmental conditions or the need for hormone treatments.
There are about 6 key stages involved in growing the channel catfish to table size
Channel Catfish Production – Egg Production Stage
Although channel catfish may mature at 2 years, they must be at least 3 years old and weigh at least 3 pounds for reliable spawning.
Fish 4 to 6 years old, weighing between 4 and 8 pounds are considered prime spawners.
Its been found that older fish tend to produce fewer eggs per body weight and larger fish may have difficulty entering the containers commonly used as nesting sites.
Spawning in nature occurs in the spring, beginning in about March in the southern part of the range and later as latitude increases.
The big adult channel catfish are stocked at a density ranging from 60-325/ha in ratios ranging from 1:1 to 1:4 (male:female) and allowed to select their own mates.
Alternatively, adult channel catfish may be paired in pens within a spawning pond.
Nests comprised of metal cans, drain tiles, wooden boxes or other types of enclosures of appropriate size are utilized to encourage the catfish to use to deposit the eggs they spawn.
You will need to check on the nests at three or four day intervals to see if any catfish eggs have been laid. Any egg masses found are collected and taken to a hatchery.
Females of 0.5-1.8 kg produce an average of 8 800 eggs/kg of body weight, with larger females producing an average of 6 600 eggs/kg.
Eggs may also be allowed to hatch within the spawning pond.
In that case, after the spawning season the adults are typically removed to another pond.
Channel Catfish Production – The Hatchery Stage
The idea behind fish farming is to try and replicate as much as we possibly can the natural environment of the fish in a controlled environment
in order to enable the catfish easily go about its daily functions and if we possibly can… speed up the growth rate of the fish.
In the wild, once egg laying and fertilization are complete,
the male catfish tends to chase the female catfish from the nesting area and tend to the eggs by fanning the mass with his fins to keep oxygenated water moving over them and
if everything is right including the temperature of the water, the eggs will hatch within 5-10 days.
The male catfish continues to guard the sac fry for several days until the yolk sacs are absorbed and the fry are able to swim about in search of food.
This process is what the hatchery stage attempts to simulate…
The most critical factor for a successful hatchery is a dependable supply of high-quality water…
Just like in the pond… the hatchery must be able to simulate an environment where clean water flows through the eggs oxygenating the eggs at the same time.
The hacheries used to produce catfish fry sometimes imitate the wild by using flow-through tanks holding about 90 to 100 gallons of water for egg incubation and fry rearing.
The egg hatching tanks are equipped with a series of paddles spaced along the length of the tank to allow wire-mesh baskets to fit between them.
One or two egg masses are placed in each basket and the paddles gently rotate through the water to provide water circulation and aeration.
The incubation time varies from 5 to 8 days depending upon water temperature.
At hatching, the fry (called sac-fry at this point) fall or swim through the wire-mesh basket and school in tight groups.
Sac-fry are siphoned into a bucket and transferred to a fry rearing tank.
Aeration in fry rearing tanks is provided by surface agitators or by air bubbled through airstones.
Initially, the sac-fry are not fed because they derive nourishment from the attached yolk sac.
Over a 3- to 5-day period after hatching the channel catfish fry absorb the yolk sac and turn black.
At that time fry (now called swim-up fry) swim to the water surface seeking food.
Swim-up fry must be fed 6 to 12 times a day for good survival and growth.
Fry are fed nutritionally complete feed for 2 to 7 days before they are transferred to a nursery pond.
Channel Catfish Production – Nursery Pond Stage
At the nursery stage… the main intention here for the fish farmer is to grow the fry to fingerlings (small fish size).
The Channel Catfish Fry tend to grow faster when stocked at lower densities .
The problem though is that growing channel catfish fry in lower densities requires more space which you might not necessarily have access to
Stocking rate is therefore a compromise between benefits of producing large fingerlings for foodfish growout and the economics of producing more small channel catfish fingerlings in less space.
It is important to fertilize nursery ponds so that they contain abundant natural foods to promote growth until the fry are large enough to switch to manufactured feeds.
A finely ground feed should be offered once or twice daily to train fish to accept the feed.
As the fish grow, feed particle size is increased.
A month or so after stocking, the fish (now called fingerlings) are fed once or twice daily to satiation, using a small floating pellet with 32 to 35 percent crude protein.
Because fingerling populations are particularly susceptible to infectious diseases,
disease management takes on added importance in this stage of production.
Survival of catfish fry to fingerlings varies greatly from pond-to-pond depending on the initial condition of the nursery pond, losses to bird predation, and the incidence of infectious diseases.
Average survival from fry stocking to fingerling harvest in excess of 60 percent across all ponds on the farm is considered to be very good.
The Channel Catfish are grown to fingerling size (3 to 8 inches long) over a 5 to 10 month period.
Fish are either allowed to continue growing in their original nursery ponds or are harvested and transferred to other ponds for growout.
Just a quick point to note:
Some farmers specialize in selling fry or fingerlings to producers of market-sized fish, while others purchase fingerlings for grow-out; however, many farmers operate their own hatcheries and grow-out operations
Channel Catfish Production – The Growout Pond Stage
The aim here is to grow the fingerlings you now have to table size that is…
to stocker-sized fish of 0.1 to 0.25 pounds or to food-sized fish of 1.2 to 2.5 pounds.
Cultural practices used for channel catfish production differ from farm to farm,
and the process of growing a food-sized catfish can take many paths after the fingerling phase.
The one-step channel Catfish production scheme
Most farmers divide fish stocks only once between the nursery phase and the foodfish growout phase.
In this scheme, fingerlings are harvested and restocked into foodfish ponds at roughly one-tenth to one-twentieth the density of nursery ponds
Because fish will be ten to twenty times heavier when harvested as foodfish.
In the single-batch system, the goal is to have only one year-class of fish in the pond at a given time.
Fingerlings are stocked, grown to the desired harvest size, and all fish are harvested before the pond is restocked with new fingerlings to initiate the next cropping cycle.
The problem with this method though is that nearly all the fish produced under this type of system reach the market over a limited period of time,
the flow of product to the market in this manner is not conducive to having fresh fish available year round.
Also, if you have a situation where all the fish you have is coming on the market at the same time… you might not be in a strong position to demand your price.
The 2-step Channel catfish production scheme
Another approach to producing food-sized fish is to divide twice between the nursery phase and foodfish growout.
The first stage involves produces a medium-sized fish called a “stocker”.
The second division is made when stockers are harvested and restocked for growout to food size.
In this type of scheme, small fingerlings (2 to 3 inches) are stocked at about 40,000 to 60,000 fish/acre and grown over one season to produce stockers weighing 0.1 to over 0.3 pounds.
The stockers are then harvested and moved to foodfish growout ponds.
The process can be maintained for several years, during which time the ponds are not drained.
As with the one-step scheme described above, there are several options for foodfish growout using stocker-sized fish.
The multiple-batch system
In the multiple-batch system, several different year-classes of fish are present after the first year of production.
Initially, a single cohort of fingerlings is stocked.
The faster-growing individuals are selectively harvested (“topped”) using a large-mesh seine, followed by addition (“under- stocking”) of fingerlings to replace the fish that are removed plus any losses incurred during growout.
The process of selective harvest and understocking continues for years without draining the pond.
Whether ponds are operated as single-batch systems or multiple-batch systems, stocking rate is best defined as the maximum fish density (number per acre) over the production period.
Under commercial conditions, stocking rate becomes an approximate goal rather than a precisely managed population variable because it is nearly impossible to know the true inventory of fish in large commercial ponds that are used for several years without draining.
There is no consensus on the best stocking rate for commercial production and rates used in the industry range from less than 500 fish/acre to more than 10,000 fish/acre.
One explanation for the wide range of stocking rates used by catfish farmers is that production goals, facilities, and resources vary from farm to farm.
The size of fingerling to stock is a critical factor in foodfish production.
Large fingerlings will reach foodfish size faster than small fingerlings, but large fingerlings are expensive because they require more time and space to produce.
In addition, large fingerlings can be difficult to obtain because most fingerling producers prefer to stock fry at relatively high densities and move fingerlings to foodfish ponds as soon as possible to avoid risk of loss to infectious diseases and predacious birds.
The best size fingerling to stock is therefore a compromise that depends on cropping system, fish stocking density, and fingerling availability.
Channel Catfish Production – The Processing Stage
The harvested cat fish are loaded into live-hauling trucks and taken to processing plants in regions where sufficient concentrations of ponds can support year-round operation of such plants.
A minority of producers process their own catfish.
Depending on your catfish size and market demand, the fish may be steaked; filleted; or sold headed, gutted, and skinned.
The market for channel catfish in the United States and most countries is now well developed.
Once considered a product of interest only in the southern states, catfish can now be found in restaurants and on menus in grocery stores throughout the nation.
The Channnel catfish is seen by consumers as being a healthy choice food.
Market expansion may be possible through development of new product forms and value added processing.
If you are interested in learning more about the spawning process, don’t forget…
source: extracts from www.fao. org and www.msucares. com