The enigma of "optimal" F8 salinity level...

The forum for puffers that either live or start in brackish biotopes: GSPs, F8s, Ceylons & more.
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The enigma of "optimal" F8 salinity level...

Post by Minipuff » Sat Feb 25, 2017 8:38 am

What are your views on the lack of concensus about salinity levels for F8 puffers? I'm quite intrigued by this, and would be happy to hear about your views and the reasoning behind it.

A few websites (like Seriouslyfish) recommend freshwater. We all "know" freshwater is a common misconception, at least for captive F8s, yet, and IUCN redlist say F8s are freshwater fish.

Even more obscure is the claim of some that full marine works well, and that it is "debated" whether or not they live in full marine as adults. Recent statement, no documentation.

Several "random" websites with fish profiles recommend SG 1.005-1.008. No documentation.

On here, there seems to be more or less agreed that low end brackish is best, like 1.003-1.005, which is supported by RTR's long term experiment, unfortunately not published. I can't find on here which other salinity levels he tested.

On the Dutch (?) puffer forum, and also by "expert(s)" on a different group, it is recently claimed that adult F8s need a salinity of SG 1.010-1.015. No documentation.

Yet another more relaxed advice is that any low to middling salinity is just fine. Recent statement by, among others, someone whom I believe is a marine biologist.

The scientific literature says little about this, at least in the the narrow selection of publications I have had access to. The only paper I can think of that mention an SG for F8, is the paper by Doi et al. (2015), and they kept adult F8s in an SG of 1.015 for several years before the spawning experiment. Spawning was induced by lowering the salinity to 1.007. Eggs were hatched and fry reared in SG 1.005-1.007. Would the fact that they actually managed to spawn them indicate that they had been kept under optimal conditions? Or maybe it was optimal for breeding, but not necessarily for long term captive life? What made those Japanese scientist keep them at that salinity in the first place? The paper does not say.

Can someone please go out and attach GPS's to those mysterious fishies and measure the salinity along their trail, during their whole life span?? I'm kind'a obsessed, sorry... :lol: :lol: :lol:

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Re: The enigma of "optimal" F8 salinity level...

Post by Pufferpunk » Sat Feb 25, 2017 10:06 am

I'll go with RTR, EVERY single time there is controversy!
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Re: The enigma of "optimal" F8 salinity level...

Post by PYRU » Sun Feb 26, 2017 12:59 pm

I agree with her. Living into late teens in low end brackish is enough proof for me.

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Re: The enigma of "optimal" F8 salinity level...

Post by Iliveinazoo » Tue Feb 28, 2017 9:52 am

There was someone on this forum that posted a photo of a Figure 8 in its natural habitat. I'm 'almost' sure that the salinity was around SG1.002 but I can't remember what the temperature was.

They most likely are predominantly freshwater fish that travel into estuaries every now and again. I would also hazard a guess that water hardness is more important than salinity in keeping Figure 8's but it is easier to guarantee harder water with the addition of marine salt.

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