Rainy season, and breeding, 44-6
peak spawning of S. niloticus 87
Recruitment, control in culture systems
236,349-50
predators to co~trol listed 313
Reduced fry production, discussed 306
Reproduction, control of 309-16
controlled by harvesting 313-4
controlled by inhibitors 314
controlled by irradiation 314
inhibited by high stocking densities 313
overpopulation and failure of intro-
ductions 56
research requirements 355-7
role of environmental factors 133-4
role of social factors 134-5
and salinity 121, 314
temperature limits 33-4
see also Breeding
Reproductive behavior, and chemical
stimuli 347
see also Spawning, Spawning behavior
Reproductive activity, role of external
factors 133-4
role of internal factors 135-9
role of social factors 134-5
Reproductive guilds or style 63-5
hierarchical system described 65
Reproductive habits, S. niloticus 4
and taxonomy 3-4
T. mariae 4
Reproductive physiology 129-40
Reproductive potential, and success of
tilapias 116-7
Research needs, in cage culture 239-40
and production of all-male hybrids
303-4
Research priorities, summarized 350
Reservoirs, introductions 24
Respirometry, and metabolic studies
160-1
Restricted distribution, of various
tilapias 23
Rice bran, in feeds 226
and pond culture 199
and semi-intensive cage culture 223-4
Rice polishings, in feeds 226
Rift Valley, tasselled tilapias an example
of allopatric speciation 8
Rivers, different types as tilapia habitats
31
slopes and distribution of tilapias 32
Ruwanda, introductions to lakes 24
Saddle back, a spinal deformity 258-9
Sahara desert, permanent water bodies as
tilapia habitats 31
St. Lucia, introductions 28
Salinity, affects reproduction of tilapias
121-2, 314
and changes in distribution 52
effect on temperature tolerance 121
euryhaline species 38
fluctuations in L. Chilwa 38
and growth and survival 121-2
in high altitude lakes 36
high in some lagoons 38
high in some lakes 38
in L. Mweru Wantipa 38
in Nemakia mangrove swamp 38
tolerance for 4 species summarized 124
tolerance and temperature 37
tolerance of various species 38-9
tolerance of various species discussed
127
variations associated with low incidence
of parasitism 101
see also Conductivity
Salmo gairdneri, compared with tilapias
in culture systems 245
Salmonids, freshwater cage culture
discussed 246
Saltatory development, and hetero-
chrony 72,74
Saprolegnia (genus), can cause severe
losses in cultured fish 256
Sarotherodon (genus), diverse feeders 41
immunological studies discussed 12-13
introductions 20
means 'brush-toothed' 4
natural distribution of genus 20
number of species about 46 332
sex determination 275-6
species used for fish culture 10-11
typified by S. melanotheron and S.
galilaeus 6
Sarotherodon (subgenus), natural distri-
bution 9
and Oreochromis (subgenus), defined
7
Satiation, in T. rendalli 172-3
Schooling 54
Scotland, experiments with cages in
lochs discussed 246
Sea bass; see Dicentrarchus sp.
Seasonal changes in feeding 42-3
Seasonal changes of habitat 52-3
see also Migration