How many F-8's in a 75 gallon Tall??

I currently house 2 figure-8 puffers with 3 bumblebee gobies, dragon goby and a few mollies in a 55-gallon. Rule of thumb for figure-8's I believe are 20 gallons per puffer, 10 gallons for any additional. Seeing as they only get to about 3 inches in size, 75 is A LOT of space for these guys! As far as personality goes, sure, housing one will make that puffer a personable little guy. But in my opinion, each puffer has their own personality. If you provide great water conditions (make sure you cycle!!!), PLENTY of cover and hiding spots, a healthy diet and consistent water changes, there's no limit to the possibilities of bringing out the personalities of these cute fish!

Be sure to read up on your husbandry. Brackish is a must. They thrive on salt. Of course, when juveniles, start out in what water they are sold in (fresh, usually). And as they mature and grow, slowly increase the salinity of the water to about 1.005-1.008. Mine usually fare well at about 1.010 - but these guys are about 2 years old and they seem to like their water a little saltier.

So, you answer your question: in a well planted, cycled 75-gallon aquarium, I would say that your safe bet in numbers is around 3-5. However, I may be wrong. Hopefully someone else will chime in and give their opinion.

If you want to keep a single figure-8 puffer (in your case, to house alone), why not go smaller and either sell or use the 75 gallon for something better suited for a bigger tank? There are plenty of other puffer species out there that can give you what you are looking for (personality and antics). Why not go Green Spotted Puffer? Unlike the figure-8 puffers growing to about 3 inches as an adult, these guy grow to about 6 inches - much better suited for the likes of 75-gallons.

Thirty gallons per F-8 is a better rule of thumb in my opinion. Although they're pretty well behaved as far as puffers go, they still need a decent chunk of territory; plus, they're messy lil guys that have a huge bio-load for their size. Mine mixes well with Knight Gobies, though, who are fun, quirky little fish in their own right, if you'd be interested in other tankmates besides just F-8's.

PS- thepufferforum.com is an AMAZING resource for anything puffer.

Why not get a single big puffer? as you said yourself they bond with their keepers when kept solely, and there are many species out there to choose from.