The Line Between 'tropical' And 'coldwater' Fish

[backtotropical]

I've always thought that this is an interesting topic and i'm interested to get a discussion going.

It appears that it's not clear cut as for example Goldfish (Coldwater) will live quite happily at 20C, whereas Guppies for instance (Tropical) will live quite happily at around 19C.

Anyone have a definitive answer?

 

[andywg]

Tropical fish would normally refer to fish that come from water between the Tropics of Cancer and Capricorn (or water with a similar temperature). Subtropical tends to cover the wartmer waters that can dip to around room temperature. I seem to recall that everything else gets lumped under temperate or coldwater. The temperate and cold water fish can live at warmer temperatures as they are foten exposed to them in nature (though requirements will increase, see below).

As noted in another recent thread, fish are far less sensitive to changes in temperature than many give credit for and can survive some periods at a colder temperature. One must remember that fish are ectothermic, their body temperature is dictated by the outside temperature; if the temperature drops then the fish will have its entire metabolism slow down (so eating and growth rates will fall somewhat) with a few notable exceptions, such as SW sharks which can maintain a higher body temperature to gain an advantage over other fish.

This is very different to humans who notice a change in temperature far more as we are endothermic, or we regulate our own internal body temperature from metabolising food.

It is noted that some reef based algae grazing fish will exhibit close to a 50% increase in feeding strikes when the water is just a couple of degrees warmer, indicating that an increased temperature can place added strains on feeding and filtration requirements.

 

[Eclecticoldsod]

Goldfish will survive happily in a garden pond with ice over the surface. It's probably a few degrees warmer at the bottom, where they lurk waiting for warmer weather, but still not far off freezing.
Temperature is, of course, directly linked to oxygen take-up and higher metabolism. It is my personal experience that [most] fish will do better at the lower end of the temperature range for the species. They will certainly live longer – this you can prove for yourself. Whether they are 'happier' or nor is not so easy to work out...

 

[Zincubus]

I have kept quite a few different TROPICAL fish in a small ( 12x7x6 ) unheated tank .
All have thrived - I used it once as a place for my ODDS and SODS .
List of fish - Golden schubert barbs , checkerboard barbs , mollies , neons , glowlights , guppies, flying fox, plecs, glass catfish,.... plus others ...and one 5 " Blue Eyed Cichlid !!

 

[Eclecticoldsod]

All depend on where you live, Zincubus. If you are in Alabama or Singapore, you are looking at chillers – if you live in Britain, it's all down to heaters in the Winter – and quite often in what passes for our bloody Summers, too..! Goldfish survive at our room temperatures, but tropicals find it a bit nippy when the central heating goes off at night...

 

[fishyfeet]

some corys like very cool water, hadly tropical, danios and wcmm are also kept in heated and unheated aquaruims quite happily, di

 

[Eclecticoldsod]

Yup, my WCMM have been breeding for years in an unheated goldfish tank. With several pregnant Zebra Danios in my heated community tank, I intend to try them in cooler water, too..!

 

[Zincubus]

Living in Manchester UK - normal room temps.

Fish always seem very healthy just not as active.