An Investigation of the Palatability of Some Marine Invertebrates 
to Four Species of Fish 
Eleanor Russell 1 
In the past, fish attractants have aroused 
attention, and "bait” extracts have been made 
which attract fish and excite them to feeding 
activity (Bateson, 1890; van Weel, 1952; and 
Steven, 1959). 
Less work has been done on repellent sub- 
stances, apart from shark repellents such as 
copper acetate (Whitley and Payne, 1947). 
The repelling action of copper acetate may be 
due to acetic acid, and it has long been known 
that dilute acids are repellent to fish (Bateson, 
1890, confirmed by Hiatt, Naughton, and 
Matthews, 1953). 
Fish accept eagerly some animal baits while 
completely ignoring others. On this basis, dif- 
ferent degrees of "palatability” ranging to 
"unpalatability” might be postulated. Among 
known unpalatable animals there are no obvious 
common factors with regard to colour or shape, 
and this suggests that unpalatability is based on 
the chemical senses. 
Many soft-bodied invertebrates are openly 
exposed to fish attack, and even in the absence 
of obvious protective devices remain un- 
molested. Some workers (Garstang, 1890^, b; 
Bullock, 1955; Thompson and Slinn, 1959; 
Thompson, 1960a) have shown that certain 
marine animals make themselves distasteful 
to predators by the secretion of diffusible "re- 
pellent” substances. 
The present investigation was undertaken to 
obtain data on the relative attractiveness to fish 
of a diversity of marine animals in southern 
Queensland. Comparisons of food preferences 
were made, following in principle the methods 
of earlier work by Stephenson and Grant 
(1957) and Blaxter and Holliday (1958). 
1 Present Address: Zoology Department, University 
of New South Wales, Sydney, Australia. Manscript 
received May 25, 1965. 
ACKNOWLEDGMENTS 
The author wishes to thank Professor W. 
Stephenson of the Zoology Department, Uni- 
versity of Queensland, who first suggested this 
problem, and who read the manuscript and 
suggested many improvements. Thanks are also 
due to Dr. R. Endean for many valuable sug- 
gestions. The work was supported from research 
funds of the University of Queensland. 
GENERAL METHODS 
Test Animals 
Two marine species, Pelates quadrilineatus 
(Bloch), trumpeter, and Torquigener hamiltoni 
(Gray and Richardson), toado; and two fresh- 
water species, Gambusia affinis Baird and 
Girard, and Carassius auratus (L.), goldfish, 
were used. Carassius was obtained from a dealer 
and the other three species were netted when 
required. 
Freshwater species were used as a control 
against the familiarity of marine species with 
invertebrates of their own environment. 
Aquarium Conditions 
Two glass aquaria (6l X 30.5 X 30.5 cm) 
without sand were used for each species. Weed 
was excluded because fish may eat it. Approxi- 
mately 20 mussels, Trichomya hirsutes (La- 
marck), were kept in each marine aquarium 
to remove sediment. Aeration was continuous 
and salinities were checked weekly. Sizes of 
the fish, their dietary types, and numbers in 
aquaria are given in Table 1. 
Maintenance Feeding 
Fish began eating after a few days and were 
maintained on prawn, Metapenaeus master sii 
(Has well) . Each day food was dropped on the 
452 
