effect of one species on the growth
of others 188
feeding rate chart 200
nursing tilapia fingerlings 193
overwintering of fingerlings 192-3
use of predatbrs to control numbers
188-9
relevance of field studies 112-3
stocking rates for predators 189
Pond culture 185-203
all-male culture 191-7
carrying capacity for S. mossambicus
187
choice of species 186-7
feed conversion ratios 199
feeding 198-200
fertilization and manuring 197-8, 202
and integrated farming systems 198,
293
nutritional value of supplementary
feedstuffs 199
use of predators discussed 201-2
polyculture 188
S. aureus 188
S. mossambicus 187
stocking biomass recommended 188
yields and prices discussed 200-1
Population fecundity, and breeding
season 45
Port Elizabeth, S. mossambicus 34
Precocial forms, in ecological terms
specialists 67
features of life style 67
Predation, in L. Sibaya 97
Predators, cause damage and losses in
cage culture 238
to control recruitment listed 313
excluded from broodstock tanks 285
in polyculture 188-9
use in pond culture discussed 201-2
stocking ratios when controlling
recruitment 313
on tilapias named 111
on tilapias in Zambezi system 94-6
Premaxilla, Lee's cutting technique
discussed 306
Pressure, and distribution of tilapias
32,51
Prevention and control of diseases 261
Previtellogenesis, and vitellogenesis 131
Primary production, very high in
L. George 109
Problems, in aquaculture reviewed 181-3,
265-7
food and assimilation efficiency
discussed 178
diseases in tilapias summarized 351
maintaining pure genetic lines 282
movement of stock across national
boundaries 182-3
prolific spawning in aquaculture 186
supersaturation of gases in aqua-
culture 41
Production, of all-male hybrids 291-8
all-male hybrid culture experiments
in Brazil 294
and cage-size discussed 245
in extensive cage culture 217
intensive cage culture ?30-7
potential in cage culture systems 240-5
semi-intensive cage culture 221-2, 224
tilapias in natural waters 105-9
Prolactin, and reproductive physiology
136
Protein, assimi!ation efficiency 152
deficiency and malnutrition 153
digestion described 149
maintenance requirement 153
most important in limiting growth 151
site of digestion 148-9
Protein content, in fish feeds 225-6
Proteus spp., and haemorrhagic septi-
caemia 255
Prymnesium parvum, toxic effects 257
Pseudomonads, and haemorrhagic sep-
ticaemia 255
Puerto Rico, bilhania vectors in
tilapid ponds 57
intensive cage culture 231
introductions 28-30
Pure genetic lines, problems of main-
taining 282
and production of all-male hybrids
280-2
Pure strains, establishment and conserva-
tion 335-6
methods for maintaining need further
development 335
most significant collections named 335
S. aureus at Kibbutz Ein Hamifrats 335
Purina Trout Chow, protein content 225r- and K- selection, and altricial and pre-
cocial forms 72
life history features discussed 63
r and K strategists, as riverine and
lacustrine populations? 111-2