> 1/ When do DGs reach sexual maturity, these are between 4 and 5 months
> old ?
About 30 mm and three months is possible. I have had males in breeding
colour at 25 mm; females tend to be 30 mm + before they spawn. They need a
good diet. Remember they are primarily herbivorous. Globular algae and it's
associated crawleys is an excellent conditioning diet.
> 2/ Is it undesirable to let siblings breed. ?
I suspect that DGs interbreed in the wild. They are often found in isolated
springs with no obvious means of regular dispersal. Edgbaston Gobies appear
to move between springs when the surrounding area floods, but this may be
once every ten years, or even less frequently. In the past I produced some
thoroughly inbred Coward Springs gobies. My population started from a single
pair of related gobies. I maintained the population for about seven years
before some fish started to show inbreeding signs. Typically these signs
were: short dorsal and anal fins, black dorsal fins (blue and yellow
colouring disappeared), short gill covers and reduced upper jaws. Most of
the fish retained the wild features. Maybe the "mutations" are selected
against in the wild? I certainly selected fish as close to the wild type as
I could.
Rob Wager
Freshwater Fish Biologist
Raintree Aquatics Pty Ltd
Aquatic Environment, Fish and Aquaculture Specialists
1002 Caboolture River Road, Rocksberg, Queensland, Australia, 4510
Phone 07 5496 7939, Facsimile 07 5497 0022, International +61 7 5496 7939
Email raintree at closer.brisnet.org.au