Dear All

Internal fertilisation in an egg-laying fish

Some months ago I asked whether anyone was aware of any records of
internal fertilisation of eggs in normally egg laying fish species. What
I meant by that was records of embryos inside the ovaries of normally
oviparous females. Thank you to those who responded. Although there are
quite a number of fish species with internal fertilisation (viviparous),
it appears that records of this occurring in species that normally lay
eggs are extremely rare. The only well documented one that I have found
is in the Japanese cottid fish Hemilepidotus gilberti, in which the
embryos fail to develop properly, see:

Hayakawa, Y., Munehara, H., 2001. Facultatively internal fertilization
and anomalous embryonic development of a non-copulatory sculpin
Hemilepidotus gilberti Jordan and Starks (Scorpaeniformes:
Cottidae). J. Exp. Mar. Biol. Ecol. 256, 51- 58.

and

Hayakawa, Y., Munehara, H., 2003. Comparison of ovarian functions for
keeping embryos by measurement of dissolved oxygen concentrations in
ovaries of copulatory and non-copulatory oviparous fishes and viviparous
fishes. 295, 245- 255.

Best wishes
Andrew MacColl

Associate Professor of Evolutionary Ecology
School of Life Sciences
University of Nottingham
University Park
Nottingham
NG7 2RD, U.K.
Tel: +44 115 951 3410
http://ecology.nottingham.ac.uk/AndrewMacColl/index.php

Andrew.Maccoll@nottingham.ac.uk