This research designed monitoring effect of increased water temperature on female O. niloticus experimentally and survey. One hundred female O. niloticus from private farm divided into four groups: 1 st kept at room temperature (Control) and 3 kept at 30, 33 and 36 ºC water temperatures respectively for 2 weeks. Two Survey groups collected from El monib at 27 ºC (Control) and other at 36 ºC water temperature. Experimental fish suffered of nervous manifestations, suffocation, detached scales, ulcers and tail rot. Postmortem lesions included unsymmetrical friable ovaries with autolysis. Females showed highly significant decrease in B.W., WG, WH, IG, K condition, relative and absolute fecundity at all experimented groups. Survey females B.L., B.W., F.B.L., F.B.W., WG and IG showed high to moderate significant increase. Oppositely, F.O.W., K condition and absolute fecundity copied moderate to high significant decrease. Among experimental groups, albumin (at 30 ºC), glucose and testosterone increased highly significant whereas albumin at 33 & 36 ºC and E2 at 36 ºC showed highly significant decrease. Survey group registered highly significant increase in albumin, glucose and testosterone. Total proteins, globulins and E2 showed highly significant decrease. Ovaries affected by increased water temperature; worst lesions appeared in survey. Ovaries showed necrosis, clumping and perforation of the chorion, fragmentation of nucleus, or cystic atretic follicles. Liver showed swollen hepatic cells. Favorable water temperature for O. niloticus fish is 27 ± 2ºC. Thus, it is recommended to use more aerators in fish ponds especially brood stocks or to be covered during summer season.