Nature and Science
Morphology, Fecundity and diet of Galeoides decadactylus (Pisces: Polynemidae) (Bloch, 1795) off Nigerian coast
*EMMANUEL B.E, GBESAN, K and OSIBONA, A.O
Galeoides decadactylus (Bloch) is one of the three species of the family polynemidae
commonly called the threadfins, found in warm tropical surface water of the Atlantic on the continental
shelf of West Africa. They are important in the trawl fisheries of Nigeria. The specimens used for this
study were collected off Nigerian coast from Lagos to Calabar between December, 2003 and
November, 2004. In this study the length-frequency distribution, length - weight relationship, condition
factor, sex ratio, fecundity, food and feeding habits of Galeoides decadactylus were examined.
Measurements recorded for each fish were standard length (SL) and total length (TL) to the nearest
1mm and weight to the nearest 0.1g. Sexes of fish were determined by visual and microscopic
examination of the gonads. Fecundity was estimated from the ripe ovaries (stage v) by the gravimetric
method. The Gonadotropic Index (GI) and the Condition Factor (K) were calculated. Food items were
quantified by two methods, the numerical and frequency of occurrence methods. The total length of
259 specimens examined ranged between 12.0cm and 28.3cm (standard length 9.9cm to 20.8cm).
Specimens exhibited negative allometric growth. The condition factor increased with individual size.
Females had a slightly higher condition factor than males. The sex ratio was 1:0.46 (male:female). The
number of eggs per female ranged between 58 001 and 279 279. There was a negative correlation
between log-fecundity and log-weight than between log-fecundity and log length. The major food
items were crustaceans, molluscs, pisces and annelids. There were no distinctions in the feeding habits of the species in relation to size. The fish was euryphagus species and highly fecund.
[Nature and Science 2010;8(3):15-23]. (ISSN: 1545-0740).
Key Word :
Galeoides decadactylus, fecundity, allometric growth, condition factor, euryphagus
Volume 8, Number 3, March 2010 , ISSN 1545-0740