PondTools

Tilapia

Tilapia in a bass pond: pounds per acre and when to stock

Tilapia are a summer fish. Stock them in spring once the water has settled above 65 degrees Fahrenheit, at 15 to 20 pounds of adult fish per acre by the extension numbers (northern forum users go to 40), and buy fish over 5 inches so the bass do not eat the whole order on day one. They breed all season, feed bass and bluegill with their young, graze some filamentous algae, and die when the water falls into the low 50s, so in most of the country they are an annual purchase, where the state allows them at all.

What the authorities say

The temperature limits come from SRAC Publication 283 (Popma and Masser): "The lower lethal temperature for most species is 50 to 52 °F for a few days, but the Blue tilapia tolerates temperatures to about 48 °F." They "generally stop feeding when water temperature falls below 63 °F," and "Reproduction is best at water temperatures higher than 80 °F and does not occur below 68 °F."

Texas A&M's Mozambique Tilapia for Biological Control of Aquatic Vegetation in Texas (RWFM-PU-393, 2022) gives the stocking rule: "Mozambique tilapia must be stocked in the spring after the water temperature has stabilized above 65 degrees F," and "the general stocking rate is 15 to 20 pounds of mixed-sex adult tilapia per acre." They "die off when temperatures dip below 50 degrees F." Where bass are already present, it says tilapia "are often not an effective form of aquatic vegetation control if there is a large bass or other predatory fish population present in the pond at stocking." On algae it is cautious. The Mozambique "normally only consumes up to 10 percent of filamentous algae as part of its diet when other food sources are present," and "tilapia stocked on their own can rarely manage filamentous algae alone." The advice is to "kill off the majority of filamentous algae mats with an appropriate chemical treatment (algaecide), and then stock tilapia to graze off any new growth." The AquaPlant algae page adds that tilapia "usually cannot be stocked before mid-April or May and will die in November or December."

Alabama Extension's Weed Management in Lakes and Ponds (ANR-0048) gives its only rate for watermeal control: "Stock 15 pounds of male and female tilapia per acre during May or June," and "In ponds with bass, stock tilapia larger than 5 inches so the bass will not eat them." Mississippi State Extension says tilapia "will not survive in ponds unless they are supplied with heated water" in most of that state. Clemson HGIC 1715 gives a count instead, "200 to 400 fish per acre in the spring." No extension source I found gives a pounds-per-acre rate for tilapia stocked purely as bass forage; every published rate is for vegetation control.

Published tilapia temperature thresholds and rates
SourceTemperatureRate per acre
SRAC 283Lethal at 50 to 52 F for a few days (blue to about 48 F); stop feeding below 63 F; no spawning below 68 FNot given for ponds
Texas A&M RWFM-PU-393Stock after water stabilizes above 65 F; die below 50 F15 to 20 pounds of mixed-sex adults
Texas A&M AquaPlantStock mid-April or May, die November or December15 to 20 pounds of mixed-sex adult Mozambique
Alabama Extension ANR-0048Die below 50 F; use restricted to May through October15 pounds in May or June, over 5 inches where bass are present
Clemson HGIC 1715Cannot survive normal winters in most of South Carolina200 to 400 fish in spring

Which species is legal where

Texas rewrote its rule in 2021. Under 31 Texas Administrative Code 57.115, "In the stocking zone no authorization or permit is required under this subchapter to purchase, possess, transport, or stock into a private pond blue tilapia (O. aureus), Mozambique tilapia (O. mossambicus), Nile tilapia (O. niloticus), Wami tilapia (O. hornorum), or hybrids between these species." In the conservation zone, "the landowner or their agent must obtain written approval from the department." Texas A&M says the two zones are "largely split by Interstate Highway 35," with the conservation zone to the west, and that "all tilapia must be purchased from permitted sellers only." Other states vary. Mississippi requires a permit, South Carolina DNR "now requires a free of charge permit" according to Clemson, Florida lists blue tilapia as a conditional species, Auburn's ANR-0577 says "In most states, tilapia cannot be legally stocked into open pond systems," and esshup (Moderator, Ambassador Field Correspondent) reports they are not legal in Illinois. Call your state fisheries agency before you call a hatchery.

What Pond Boss members do

JohnK's 2010 thread asking whether anyone had stocked tilapia and what they saw has drawn about 97,000 views. Dave Davidson1 (Moderator) opened with the line everyone repeats: "They're not a magic bullet but I don't recall any negatives." Hal Johnson (Lunker) put 10 pounds into an acre golf-course pond he "could walk across because of FA" and had it fishable in under 90 days. scott69 (Lunker) saw less surface scum but his bass stayed "skinny as a rail" while the bluegill grew.

The magazine number is 20 pounds. Bob Lusk (Editor, Pond Boss Magazine) says that in north Texas "20 pounds per acre is what it takes to control filamentous algae," and reports that rate giving algae control and higher survival of young-of-the-year bluegill into fall. Farther north the rate doubles: esshup in Indiana saw no algae control at up to 20 pounds per acre and got it at 40, and calls it "an all or nothing thing." Bill Cody (Moderator, Ambassador Field Correspondent) sells them, and says fish of 4.5 to 6.5 inches run 4 to 5 to the pound at 20 to 30 dollars a pound, and he stocks 30 pounds per acre for heavy algae and 15 for light. Stocking more than that does not help. FireIsHot (Moderator) finds 20 to 30 pounds per acre right and says 60 to 70 did not help another owner; Dave Davidson1 "tried 70+ pounds per acre and got our butts kicked" in Texas.

For timing and size, Bill Cody waits until the water "stabilizes at 68F-70F," and buys fish of at least 5 inches, better 6 to 8; FireIsHot stocks Mozambiques at 65 F. esshup wants 6 inch fish, since a bass needs to be about 18 inches to eat one.

The forum's view of what tilapia do for bass is indirect. Bob Lusk is "about 80% convinced that tilapia aren't a primary diet source for bass"; the gain comes because predators eat tilapia fry instead of bluegill fry. FireIsHot reports that by fall no tilapia were left but the breeders, and thousands of 2 to 3 inch coppernose lined the banks. esshup offers a counterexample: 40 pounds per acre of mostly males controlled algae but added no bluegill recruitment. Come fall, ewest (Moderator, Hall of Fame 2014) says bass gorge on dying tilapia just before winter, esshup wants that die-off, and Bill Cody angles them out before the water drops to 62 to 65 F.

Where the tiers differ

Extension's 15 to 20 pounds per acre and the magazine's 20 agree for Texas and the Deep South. The 40 pounds northern users swear by has no extension basis; it is a reported outcome from a short season. The "50 to 100 pounds per acre for bass growth" figure that circulates online comes from hatchery marketing, and no agency document supports a forage rate at all. Rainman (Ambassador Field Correspondent, Hall of Fame) puts pure blues dying at 42 to 48 degrees and hybrids at 52 to 58; SRAC gives blues "about 48 °F" and the rest 50 to 52. The biggest gap is on algae. Texas A&M says tilapia alone "can rarely manage filamentous algae," while moderators report clean ponds at the right rate. Both can be true: the diet studies describe a fish with other food available, and the forum successes usually follow an algaecide knockdown or a rate that leaves the fish little else.

What to do

  1. Check legality first. In Texas, find which side of Interstate 35 you are on, and if you are west of it get written approval from Texas Parks and Wildlife before you buy fish. Buy only from a permitted seller and keep the invoice.
  2. Decide the purpose. For algae, kill the existing mats with an algaecide, then stock. For forage, expect the benefit as fatter bluegill and better bass condition; the bluegill article covers how tilapia spare bluegill fry.
  3. Wait for a surface temperature that holds above 65 F for a week, 68 to 70 in the North.
  4. Pick the rate: 15 to 20 pounds per acre in the South, 30 to 40 where the season is short, and no more. Buy fish at least 5 inches long, 6 or more if the pond holds 18 inch bass. The PondTools carrying-capacity calculator (also standalone) takes pond area in acres, water fertility in five steps from clear to fed and aerated, and region, and returns the pounds of fish the pond can hold, so you can see what a summer crop adds to the bass and bluegill already there. The PondTools stocking-plan calculator (also standalone) takes area, whether you fertilize, the goal, the region and whether to include redear and catfish; tilapia supplement that plan.
  5. In fall, fish them out while the water is above 62 F if you want the meat, or leave them for the bass. Expect to buy again next spring anywhere north of the Gulf Coast.
  6. Do not stock a few dozen fish into a pond already choked with algae, do not stock ahead of a cold snap, and do not put small fish in with adult bass and expect survivors.

Sources