Blue Tilapia (Tilapia aurea) were introduced to Florida in 1961. Subsequently they have become established throughout the central part of the state. Tilapia were first collected from Lake Tohopekaliga in 1976. Since that time a considerable expansion in both numbers and biomass has been documented. The juvenile tilapia population has increased by a rate of approximately 500% per year from 1979 to 1981. Blocknet samples taken in the fall of 1981 indicated that young of the year and adults of this species conservatively comprised 0.5% by number and 16% by weight of littoral zone fish populations. Experimental gill nets of 127-, 152- and 178-mm stretch mesh have proven effective in sampling limnetic tilapia populations.