Cobalt Blue Goby

Description

The gradient of the streams varies depending on locality, andStiphodonspp. inhabiting the fastest-flowing and/or living above waterfalls generally lack extended dorsal-fin rays/spines plus the first dorsal-fin is rounded in shape and approximately the same height as the second dorsal-fin.

In contrast those possessing a taller first dorsal-fin with one or more extended rays (characters usually if not always more apparent in males) tend to live in slower-moving streams and not climb waterfalls as part of their life cycle (Watson, 2008).

S. semonifalls into the former group and typically occurs in higher altitude biotopes characterised by rapidly-flowing, narrow runs and riffles broken up by wider-slower-moving stretches, usually located above waterfalls or cataracts.

Substrates are normally of bedrock with scattered jumbles of rocks and boulders, and while riparian/stream-side vegetation and submerged leaf litter are common aquatic plants arent usually present.

Evidence exists to suggest that differentStiphodonspp. actively choose a particular substrate type over another, with some appearing to focus on rocks/boulders within a particular size range for example.

The range of substrate sizes chosen by females also appears to be significantly narrower than that for males in some cases, so resource partitioning may be occurring between and/or within species depending on locality.

The most favourable habitats all contain very clear, well-oxygenated water which, allied with the tropical sun, facilitates the development of a rich biofilm carpeting submerged surfaces.

Sicydiines are such successful colonisers of these niche environments due to aspects of their morphology which allow them to both utilise this as a food source and employ a remarkable breeding strategy.