Robert Durborow, State Extension Specialist for Aquaculture, Kentucky State University
Adult largemouth bass. Photo: Dr. Rusty Wright, Auburn University.
Largemouth bass (LMB) are cultured for food fish and pond stocking. They can bring prices as high at $6.00 per pound (live weight) for the grower and can be grown at a wide range of temperatures. Some states (e.g., New York and Mississippi) prohibit LMB sales (probably because they believe that sales would encourage illegal capture and sale of wild bass), so make sure that your state allows their culture and sale. Challenges include the fact that LMB need to be feed-trained, and their feed can be expensive due to the high protein levels needed. However, the prices that LMB growers can receive seems to more than offset these costs.
The production cycle at latitudes similar to Kentucky's are shown in the table below:
|Spawning in a pond||May through June|
|Stock fry in established nursery pond||June|
|Feed-train the young largemouth bass in tanks||June through July|
|Grow out to fingerling size during first year||June through November|
|Grow out completion to market size||March through November in 2nd year|
Egg production can be estimated at 5,000 to 10,000 eggs per pound of female brooder. Eggs can be left in the pond to hatch or transferred to a separate nursery pond on the spawning mats. Eggs usually hatch 2 to 3 days after spawning (with about 75% rate of survival). They will use up their yolk sac and be ready to feed (swim-up stage) 3 to 4 days after that with about 60% surviving.
When they are ready to feed, they seek out zooplankton (e.g., copepods and rotifers) and will not accept artificial feed. If not enough zooplankton is available, the LMB fry will cannibalize each other; to avoid this, their nursery pond should be fertilized about 2 weeks before fry are stocked with 250 lb/ac of organic fertilizer such as soybean meal or alfalfa pellets followed by 15 lb/ac the following week. There should be at least 100 zooplankters per liter of pond water.
Fry can either be moved into their own weed-free fingerling pond (using soft mesh seines) separate from the brooders, or they can be left in the original pond and the brooders can be moved. Fry should be at a density of between 40,000 and 100,000 per acre in the nursery pond.
When the bass reach 1.5 to 2 inches in length, they begin to switch their diet from zooplankton to insect larvae and eventually smaller fish. At this point in their development, the LMB can be feed-trained to accept formulated diets.
The LMB are:
The replacement/transition to formulated diet is done over a 7-day period, and the fish are fed 2 to 8 times a day at about 15% of their body weight. Use the following table as a feeding guide:
|Day 1 - 3||100% Krill|
|Day 4 - 6||75% Krill : 25% Formulated Feed|
|Day 7 - 9||50% Krill : 50% Formulated Feed|
|Day 10 - 12||25% Krill : 75% Formulated Feed|
|Day 12 - 26 (or longer)||100% Formulated Feed|
As indicated in the last row of the table above, the LMB are fed straight formulated diet in tanks for at least 2 weeks until they are stocked into a pond. This whole feed-training process works best at higher temperatures (80° - 86°F water temperature) and under good water quality conditions (dissolved oxygen > 4 mg/L, temperature < 89°F, ammonia < 1 mg/L).
The feed-trained LMB should be stocked at 50,000 to 100,000 per acre and fed a 40 to 48% protein (and 8 to 10% fat) salmonid diet 2 to 3 times a day to satiation. Using a floating diet is important in order to observe when the fish stop feeding and to keep the pellets in the fish's "strike zone" for longer. If the bass are at least 1 gram each in size, feed them a 1/16-inch floating pellet (smaller bass < 1 g should get a smaller #1 or #2 crumble pellet). Using this schedule, the bass should reach 3 inches by early fall and can then be stocked into grow-out ponds at 10,000 to 20,000 per acre.
Move the bass only when water temperatures are above 55°F; handling at lower temperatures usually results in severe fungal infections. An alternative plan is to stock the newly feed-trained bass directly into the grow-out pond at 10,000 to 20,000 to the acre. At these grow-out densities, the bass should reach 1/4 pound by November of their first year.
During this first-year grow-out, they should be fed twice a day (an hour after sunrise and an hour before sunset) to satiation with a feed having a protein level above 40% and a fat level above 15%. This feed often contains > 35% fish meal and costs at least $750 to $1,000 per ton. Recent research has shown that fish meal can be reduced to about 8 to 10% when replaced by poultry by-product meal.
Keep carbohydrate levels below 20% because LMB do not handle high carbohydrates very well. At this low level, however, feed pellets do not float very well, and the bass must be fed slowly to give them time to get to the pellets before they sink.
At the end of year one or the beginning of year two, the LMB should be thinned out to about 3,500 to 4,500 per acre; they should reach a 1-lb harvest size at the end of this second growing season. As mentioned before, move the bass only when water temperatures are above 55°F to avoid fungal infections. The following table shows the ideal water quality for LMB during their second year of growth:
|Water Quality Parameter||Ideal Range|
|Dissoved oxygen||> 4 mg/L or ppm|
|Temperature||68 - 86 °F|
|Ammonia||< 0.5 ppm of toxic (un-ionized) ammonia - NH3|
|Nitrite||Very tolerant of NO3; will probably not be a problem|
Tidwell, J., S. Coyle and N. Cochran. 2011. Largemouth Bass: Production Technologies for Aquaculture. Southern Regional Aquaculture Center (SRAC) Fact Sheet/PowerPoint presentation at website: Largemouth Bass Production Technologies for Aquaculture (ppt).