in interspecific spawnings 322-4
S. aureus 319-21,323
S. niloticus 320-3
S. vulcani 318, 320
Spawning grounds, choice of 46-7
Spawning performance, factors affecting
discussed 327-9
Spawning seasons, and environmental
factors 133-4
Speciation, in L. Barombi Mbo 8,331
and immunological studies discussed
12-3
in L. Jipe 332
in Sarotherodon and Tilapia 8-9
and taxonomy 3-13
Specific and generic names, some origins
4,6
Spermatogenesis, controlled by a
gonadotropin 135
spermiogenesis, and spermiation 131
Spermatozoa, development 131
Spinal deformities 258-9
Sporozoa, common in wild tilapias 249
Springs (hot), tilapia habitat 31
Sri Lanka, introductions 28,30
has ten thousand small reservoirs 182
Starvation, metabolism and loss in weight
164-6
studies on T. rendalli 164-5
Stenothermal species 37
Steroid hormones, and monosex culture
311-2
Stirling (Scotland), studies on diseases
and parasitism in tilapias 247-63
Stock transfers, need for national
controls 261
Stocking, biomass recommended 188
and young-of-the-year culture 189
Stocking data, intensive cage culture
231-5
Stocking densities, all-male culture 195
all-male hybrid culture in Brazil 294-5
extensive cage culture 217
polyculture of all-male hybrids 300
production of fry and fingerlings 214-5
semi-intensive cage culture 222,224
Stocking ratios, when using predators to
control recruitment 313
Stomach fluid, low pH in tilapias 146
Storms, and massive fish Fils 40
Streptococci, B-haemolytic and haemorr-
hagic septicaemia 255
Stump body, a spinal deformity 258-9
Stunting populations, listed 74-5
see also Drawf populations
Stunting 78-80, 336-40
in hot springs explained 174-5
may follow stocking by weight 187
of S. mossambicus in Malawi 187
Subgenera, merits of opinions discussed
7-8
Subgenera defined, behavioral and geo-
graphical evidence 7
Subgeneric names, need not be used by
fish culturists 7
Substrate brooders, and scheme of
reproductive guilds 66
see also Substrate spawners
Substrate spawners, advantages 48-9
behavior 46
dependent on shoreline habitats 51
life history compared with mouth-
brooders 70-1
mucopolysaccharides glue eggs to
substrate 132
nesting zones 47
T. rendalli 46
T. zillii 46
vulnerable to changes in water level 50
young precocial at first feeding 67
Sudanese irrigation channels, introduc-
tions 24
Supersaturation, and gas bubble disease
257
Survival, of fry in mass production
techniques 215
Survival value, of daily changes in habitat
53
Swampy lakes, as tilapia habitats 31
Swimbladder, adaptation to pressure
limited 32
use as an oxygen store discussed 127
Swimming performance, and distribution
34
Sympatric speciation, in L. Barombi
Mbo 8,331
and heterochrony 73
in Malagarasi swamps 8
and Malawi flock species 8
Sympatric species, confusion with intro-
ductions 24
Systematists, and use of subgeneric
names 7Taiwan, intensive cage culture 235-6
introductions 28-30