brooding areas 47
evolved from substrate brooders 68
and genetic markers 269-77
guarding the young 48
larval period eliminated 64
life history compared with that of
substrate spawners 70-1
males and nesting zones 47
origins 331
production of unusual sex ratios 269
roles of males and females 6
S. karomo 47
S. macrochir 47
S. mossambicus 47
S. variabilis 4 7
schooling of alevins 54
spawning behavior 47-9
young altricial at first feeding 67
see also Guarders, Parental care
Mouthbrooding, advantages 48
and feeding 43
polyphyletic origin? 62
MP, average monthly production 219-20
MSG, monthly specific growth rate 218-20
MSP, see Male sex-protein
Mucus, autoallergic properties in S.
mossambicus 313
Mud fish, see Ophicephalus striatus,
Channa striata
Mugil cephalus, in polyculture 193-4
Mullet, see Mugil cephalus
Mutanda (Uganda), introductions and
altitude 36
Mycobacterium fortuitum, and tuber-
culosis in cichlids 256
Mycobacterium tuberculosis, and disease
in tilapias 254
Mycotic infections 256
Myxobacteria, and diseases in tilapias
254-5
Myxosporidians, recorded from wild
tilapias 249
Namib desert, permanent water bodies as
tilapia habitats 31
S. mossambicus in water bodies 25
Nanism 110
Native species, to be checked before
importing stock 11
Natural distribution, importance of
knowledge 21
Natural environments, for fingerlings in
all-male hybrid production 283-90
Nematode parasites 252-3
little known of their significance in
tilapias 252
Neoplasia, lack of detailed observations
258
Neoteny, survival value for tilapias 77
Nesting zones 46-7
New Guinea, introductions 28
Nicaragua, introductions 28
Nile perch, see Lutes niloticus
Nilotic species, growth rates 103-5
in rivers and lakes 85-91
Nocturnal feeding, in various species 43
Nomenclature, genera Sorotherodon and
Tilapia accepted for Conference
proceedings 353
Notropis lutrensis, in hot springs 34
Nuclear power station, S. niloticus in
warm water 29
warm effluent used for cage culture
207,218
Nursery areas, competition between
species in L. Victoria 93
Nursing of fingerlings, in all-male culture
191-3
Nutrition, 340-6
research requirements 357
Nyasalapia (subgenus) 7
natural distribution 10
species are cultured 10Oasis (southern Tunisia), introductions 24
Oil cake, and semi-intensive cage culture
223-4
Oocyte, development 131
growth described 131
growth in T. rendalli 132
Ophicephalus striatus, predator in poly-
culture 189
predator on young tilapia 313
see also Channa striata
Oreochromis (subgenus), natural distribu-
tion 10, 17
species are cultured 10
Oreochromis, a new genus? 6, 11
Oreochromis hunteri, maternal mouth-
brooder 7
on Mount Kilimanjaro 6
Oreochronzis and Sarotherodon, sub-
genera defined 7