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Suitability of Water temperature in tilapia culture

The intolerance of tilapia to low temperatures is a serious constraint for commercial culture in temperate regions. The lower lethal temperature for most species is 50 to 52o F for a few days, but the Blue tilapia tolerates temperatures to about 48o F. Tilapia generally stop feeding when water temperature falls below 63o F. Disease-induced mortality after handling seriously constrains sampling, harvest and transport below 65o F. Reproduction is best at water temperatures higher than 80o F and does not occur below 68o F. In subtropical regions with a cool season, the number of fry produced will decrease when daily water temperature averages less than 75o F. After 16- to 20-day spawning cycles with 1/2-pound Nile tilapia, fry recovery was about 600 fry per female brooder at a water temperature of 82o F, but only 250 fry per female at 75o F. Optimal water temperature for tilapia growth is about 85 to 88o F. Growth at this optimal temperature is typically three times greater than at 72o F
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Health Articles

An Open Letter regarding recent reports that low-fat fish like tilapia are unhealthy. (July 16, 2008)

Eating fish, especially oily fish, at least twice per week is recommended for heart disease prevention. Fish is low in total and saturated fats, high in protein and essential trace minerals, and contains long-chain omega-3 fatty acids (EPA and DHA). Oily fish rich in these healthy omega-3s include salmon, trout, albacore tuna, sardines, anchovies, mackerel and herring. Our omega-3 needs can also be met by eating less-oily (lower-fat) fish more often.

Tilapia and catfish are examples of lower-fat fish that have fewer omega-3s than the oily fish listed above, but still provide more of these heart-healthy nutrients than hamburger, steak, chicken, pork or turkey. Actually, a 3 ounce serving of these fish provides over 100 mg of the long chain omega-3 fatty acids EPA and DHA. Considering that this is about the current daily intake of these fatty acids in the US, even these fish should be considered better choices than most other meat alternatives. Since they are also relatively low in total and saturated fats and high in protein, they clearly can be part of a healthy diet.

US Department of Agriculture statistics indicate that farmed tilapia and catfish contain somewhat more omega-6 fatty acids than omega-3. Most health experts (including organizations such as the American Heart Association and the American Dietetic Association) agree that omega-6 fatty acids are, like omega-3s, heart-healthy nutrients which should be a part of everyone's diet. Omega-6 fatty acids are found primarily in vegetable oils (corn, soybean, safflower, etc) but also in salad dressings, nuts, whole-wheat bread, and chicken.

Replacing tilapia or catfish with "bacon, hamburgers or doughnuts" is absolutely not recommended.

Signed:

William S. Harris, PhD, FAHA
Sr. Scientist and Director
Metabolism and Nutrition Research Center
Sanford Research/USD
Sioux Falls, SD
(605) 328-1304