Organic fertilizers, and production of
all-male hybrids summarized 295
Organic matter, site of digestion 148-9
Oxygen, and distribution of tilapias 40-1
and distribution of young tilapias in
L. Victoria 93
fish size, metabolic needs, and
growth 338
low levels tolerated 40
and S. mossambicus 40
and S. niloticus 40
supersaturation in L. Chilwa 41
Oxygen tolerance, physiological and
behavioral basis 40
Oyster shell, in artisanal feeds 226
Paedomorphosis, and development 72
Panama, all-male hybrid production 286
Panicum repens, food of T. rendalli in
L. Kariba 168
Paraguay, introductions 30
Parasites, behavior of Argulus sp. in
cages discussed 246
cestodes not a serious problem in
cultured tilapias 252
crustaceans 253-4
helminths 250-3
infected fish can harm man 251
may be spread by introductions 57
and mortality in S. niloticus 236
myxosporidians discussed 262
nematodes 252
Parasitic diseases 248-54
protozoan parasites 248-9
Parasitism, low incidence attributable to
varying salinity 101
Parental care, and diet 4
role of males and females 6
see also Mouthbrooders
Parental roles, discussed 68-70
Paretropus petiti, valuable fish almost
disappeared after tilapia intro-
ductions 57
Partitioning of resources, L. Bosumtwi
99
L. Victoria 92
Paternal mouthbrooder, S. melano-
theron 6
Peanut oil cake, in feeds 226
Pelecanus onocrotal~s roseum, pelican
on L. Nakuru 101
Pelleted chicken feed, in pond
culture 199
in polyculture of all-rnale hybrids 300
Pelleted rations, optimistic growth fore-
casts could mislead 170
Pelleted versus mash feeds 228
Pellets, experiments with different types
228-9
Pentecoste (Brazil), ponds and pig sties
worked together 293
precautions to preserve pure genetic
strains 285
Rodolpho von Ihering Fish Culture
Research Center 308
Periphyton, in diet 144
Peru, introductions 30
pH, and distribution of tilapias 40
lethal limits for tilapias 123
tolerances discussed 125-6
Pharyngeal apparatus, role in digestion 142
Pheromones, and spawning discussed 140
Philippine lakes, extensive cage culture of
S. mossambicus 217
Philippines, intensive cage culture 232,
235
introductions 28
unfavorable effects of introductions 57
Phosphorus, removed from L. Nakuru by
pelicans 101
Photoperiod, practically constant in
L. Naivasha 45
Physical factors, and distribution of
tilapias 31-41
Physico-chemical factors, and abundance
of tilapias 109
Physiology, of oxygen tolerance 40
Physiological studies 115-80
Phytoplankton, in diet 144
eaten by S. esculentus 41
eaten by S. rnacrochir 41
Pig fattening, and pond culture 198
Pigs, and all-male hybrid production in
Brazil 293
teratogenic effect of methallibure 314
Pituitary, and control of reproductive
activity 135-6
its activity is regulated 138-9
Plant leaves, and semi-intensive cage
culture 223-4
Poaching, and cage culture 209, 239
Pollution, and cage culture 239
Polyculture, all-male hybrids 296-8
details summarized 190