I had a figure 8 in my community tank, I was assured by the pet store owners that it would go great in my tank, but I had to remove it because it was getting very nippy towards my other fish. It almost ate my irridescent shark alive, even though the shark was twice as big. I have since changed my tank over to Cichlids and an Oscar along with a few loaches and a bumblebee catfish, and now he gets along great with them. So i dont recomend getting this fish for a community tank.
These fish are strictly brackish water fish. I have seen too many people saying these fish can thrive in fresh water. They can live up to 18 years in brackish water, up to 4-5 in fresh water. These fish need hard-shelled foods, like snails and shrimp, once every week at least. These fish are compatible with other brackish puffers, bumblebee gobies, and knight gobies. They grow to about 8-10 cm and need about 40 L per Figure 8 puffer. They should not be fed guppies as this will result in fatty liver and death!
One of the peculiar species of the aquarium trade/hobby. These fish are freshwater, though they thrive in brackish or full marine, I believe it is better for nature to take its place, since figure 8 puffers are wild-caught in Southeastern rivers. In my experience, these fish are intermediate care, and expensive. They need a neutral pH, and immaculate water chemistry. Decent water changes, aquarium upkeep a must. The most demanding aspects of these fish are its diet. It should consist of shellfish, worms, and other meaty foods. But once you got the dime and the time, it will kindly return the love invested in it back to you. These little buggers are curious, and a marvel to an aquarium. I currently have a figure8 puffer in my 80 L tank and is doing well. They express their affection to you by showing off their best colours and attitudes.
I have owned a f-8 puffer for 3 years now and he's got to be one of the most interesting fish I have ever owned. He started out in my 250 L fresh water tank with larger, peaceful fish and three rope fish. One day I noticed he wasn't doing well, his color was fading, and he refused food (something a puffer of any sort should never do) so I set up a 120 L brackish tank and in no time he was his old self again, but with brighter coloration. Now he lives with 3 orange chromides and a violet goby. I feed him Aquadine shrimp pellets, spirulina, and shellfish for his fused teeth. I never feed live fish because of the diseases they can bring. Plus, then he will not associate his tankmates with food.
I just absolutely love F8's...they're such a cute fish. The F8 that I have, Squishy, has been really good about changes. At one point in time I had him in an 8 liter tupperware container for about 4-5 days when I was moving 2400 km, he did just fine. All I did was keep him fed, keep a bubbler going, his heater at a decent temp and of course it was a bit tricky keeping his water clean because he's such a messy eater. My F8 loves blood worms. He also likes to nibble on snails, which I give him one or two maybe once a month. One thing I learned with snails in F8 tanks is: don't keep the snails in the tank for more than just a couple of weeks, because the snails can get the water pretty dirty once they have died. My F8 gets to his snails pretty quick, so he usually has them eaten up and gone within a week or two. Other than that, my F8 has been a very friendly and fun fish to watch. I've read you're supposed to keep them in brackish water, mine's been in freshwater with a couple of tablespoons of aquarium salt mix with every water change. He's in a 75 L and just loves it. I bought greenish reptile branches for him that I weighed down in the tank with rocks along one side and a few plants on the other. He likes to hide, especially when he's napping, but he also loves cruising the walls of the tank a lot so you have to keep a good amount of space open for them. Right now my F8 is about 9 cm long and he's pretty big compared to most of the F8's I see at the fish stores.
I too have kept my puffers in full marine. They seem to enjoy the liverock and scenery as it is very complex. I even keep them with Lionfish, and they do not nip. They are wonderful puffers to keep, especially for a beginner! They should have fairly large tanks with many complex hiding spots and broken lines of sight.