I can't get over all of the conflicting information on the internet about Figure 8 Puffers. Me and my wife decided finally to purchase 4 F8 puffers from our LFS and they seem to be happy and healthy readily taking frozen bloodworms. They are only about .5 inch long at the moment are in full fresh water in their own 29g tank (upgrade to come later).
Anyways, while looking for info on the net I have seen adult lengths anywhere from 2.5 inches to 7.5 inches! That's a heck of a difference. Also I have seen people say that F8 puffers require 1.005-1.008 SG while some owners swear they are freshwater and theirs do much better straight freshwater. WTH.
How do I decipher this conflicting information and who do I believe?
Adult size of a F8 would be 2.5-3". I will make an assumption here that F8's described at 7.5" were most likely Ceylon Puffers which can be easily mis-idientified as F8's if you dont know what you're looking for.
RTR's the man for answering your saltwater or freshwater question. He's done the most research and tank hours on this particular puffer.
F-8's, as with many puffers, have been mis-ID'd in the hobby and in science. The sizes given by Hilly are correct, larger fish are very likely incorrectly ID'd. The species name tells the tale - T. biocellatus, meaning "two eyespots", one just below the dorsal fin, one on the caudal peduncle just in front of the caudal fin. The two spots (on each side of the fish) are ocellated - essentially ringed in contrasting color*. With those spots, it is an F-8; without those spots, it is not. The back markings, from which the common name derives, are trivial for ID - each fish is uniquely marked. Only very rarely is reasonable taxonomic certainty so available to hobbyists.
The fish is FW in the wild, and as with other large-river fish and common to many such puffers, it ventures into brackish and likely SW (it in not that limited in distribution in the wild). But in captivity (for whatever reason) it does far better in low density BW than in fresh. In FW in captivity the fish is prone to skin and eye issues and rarely if ever makes it to a decade in captivity. In light BW (~1.003 specific gravity), the average fish which makes it through QT, and is not killed or stressed by tankmates, will exceed ten years in lifespan and can make it to the upper teens - huge difference there. Dr. Ebert reports essentially the same conclusion in his book - that these fish should be in BW** in captivity. I have no clue as to the mechanism(s) involved, but it does work.
*i.e., looking not unlike human eyes - dark pupil, contrasting iris, contrast again with the sclera (the white of the eye). In the F-8 (or other ocellated fish) it is dark center, different colored ring, surronded by the background body color.
**Dr. Ebert I believe uses 1/4 strength SW (approximately 1.006), so just a bit heavier than my usual 1.003 - 1.005. But I do consider anything up to 1.008 as still light BW, and I doubt that there would be any significant differences.
HTH
Last edited by RTR on Mon Mar 19, 2007 5:54 pm, edited 1 time in total.
I own a couple of F8s and have done my share of research from various sources and this forum consistently gives the most reasonable and considered and in my opinion accurate advice and opinions.
