some species cannot adapt to increased
pressure 32
spawning behavior 46-9
species with restricted distribution 23
species for which there is ecological
information listed 86
stunting 336-40
substrate and mouthbrooders 4
suitable for aquaculture 157
taxonomy and speciation 3-13
tolerance of pH 123
total number of species a matter of
opinion 332
usually hybridize relatively easily
334
variability in feeding 42
views as to merits of subgenera 7-8
world productian 185
yield in natural waters 105-9
Tolerances, ammonia 123
dissolved oxygen 122-3
pH 123
salinity 121-2, 124
temperature 120-1,125
Toxic conditions 257-8
Toxic effects, and agricultural by-products
discussed 305
Toxic substances, tilapias rather resistant
4 1
Transferrins, use as serum markers 270
see also Serum transferrins
Transfers, a cause for concern 354
ecological effects 55-7
see also Introductions
Trash fish, tuberculosis infections 256
Trewavas (Dr. Ethelwynn), views on
classification 11-12
Trichodina spp., and diseases in cultured
tilapias 249
Trichodinella spp., and diseases in
cultured tilapias 249
Triglyceride, declines as condition factor
falls 163
Tripartiella spp., and disease in cultured
tilapias 249
Triple superphosphate, and all-male
hybrid production 291-3, 295-6
Tsetse fly, in L. George area 336
Tuberculosis, could cause severe losses
in intensive culture 25
Tunisia, introductions 24
Turbidity, tilapias have high tolerance 41
Type species, S. melanotheron 6
Uganda, all-male hybrid production
288,291
introductions to lakes 24
United States of America, introductions
28-31
Upemba, introductions and altitude 36Vaccination, could protect cultured
tilapias against viral diseases 256
Valle del Cauca (Colombia), introduction
of T. rendalli 30
Vegetation, controlled by introductions
24
Vertebral count, in various species 5-7
Vietnam (North), introductions 28
Vitellogenesis, controlled by a gonado-
tropin 135
and day length discussed 139-40
Vitellogenin 131Water content, and condition in
T. rendalli 164
Water currents, and distribution of
tilapias 32-3,51
and S. mossambicus 51-2
Water exchange rate, and feed conversion
ratio 230
Water level, and size at first maturity of
S. andersonii 110
substrate spawners vulnerable to
changes 50
West Africa, T. dageti 5
West African crater lakes, ecological
studies 99-100
West African lagoons, ecological studies
10 1
S. melanotheron 37, 86
West Java, extensive cage culture of
S. mossambicus 220
Wheat flour and middlings, in feeds 226
White grub, a metacercarial infection 251
White spot or Ich 248
Wounds, and territoriality 49Xanthophyllum spp., edible tubers used
in semi-intensive cage culture 221