Stella Posted February 14, 2007 Report Share Posted February 14, 2007 I have native fish including bullies. These guys have two dorsal fins. For the last five minutes it has completely driven me nuts - what use could two dorsal fins possibly have? (havent attached a pic before, hope this works.... Anyway, this is a male upland bully showing his two dorsals, the first has a pretty green stripe) Stella Quote Link to comment Share on other sites More sharing options...
Stella Posted February 14, 2007 Author Report Share Posted February 14, 2007 ok, not working, can anyone help me with what I did wrong? Sorry, I did read the instructions.... Quote Link to comment Share on other sites More sharing options...
Caryl Posted February 14, 2007 Report Share Posted February 14, 2007 The dorsal fin keeps the fish upright, serves to protect the fish against rolling and assist in sudden turns and stops. Is it possible those with 2 live in more turbulent waters or swift currents? Never thought about it before. Quote Link to comment Share on other sites More sharing options...
Stella Posted February 14, 2007 Author Report Share Posted February 14, 2007 well, one species lives in very turbulent water, the rest in streams and rivers (some in lakes). From what I see in my tank they are not fans of current. THey are weighted to sit on the bottom and can often be seen getting pushed over by the current. Stella Quote Link to comment Share on other sites More sharing options...
fishy_t Posted February 14, 2007 Report Share Posted February 14, 2007 Two dorsals help reduce drag. Lots of Pelagic fish (fish that live in the open ocean) have this type or dorsal arrangement as it makes them more streamlined and therefore more efficient. I'm guessing this might be useful for bullies as they often live in rapid water and so being more streamlined means they are less likely to be washed away! But I would say its probably due to the fact the NZ freshwater species are all relatively 'young' (ie evolved/speciated recently compared with most freshwater fish) This means that the Bullies are probably still quite closely related to the fish they evolved from (Saltwater Gobies/Tripplefinns maybe?!) and so have retained this type of finnage... Just my theory anyway! Quote Link to comment Share on other sites More sharing options...
Alan Posted February 14, 2007 Report Share Posted February 14, 2007 Helps in cornering. Quote Link to comment Share on other sites More sharing options...
hogyn Posted February 18, 2007 Report Share Posted February 18, 2007 I've been 'bullying' since I was 8 years old. The first question that I asked about bullies was indeed why they had two dorsal fins. I've always believed that it was for quick manoeuvring in the fast flowing water systems. Sleeping with the Fishies Quote Link to comment Share on other sites More sharing options...
fishboi Posted February 18, 2007 Report Share Posted February 18, 2007 could it just be an over sized Adipose fin? Quote Link to comment Share on other sites More sharing options...
fishy_t Posted February 21, 2007 Report Share Posted February 21, 2007 Nah, I think they are still classed as the dosal(s) cause the adipose is always fleshy... (i think!?!?!) Quote Link to comment Share on other sites More sharing options...
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