I'm turning my 29G tank with 3 F8s from freshwater into brackish at the moment. I have them for only 3 weeks and I'm new to puffers too. It's not that much more difficult than keeping freshwater fish in my opinion. Just some preparation is what it needs. I did some research and posted questions in this forum. So far this is what I've learned.
1) 10 gallon per puffer, it might become a single species tank if your puffer is aggressive. Some people said they can keep F8s with Bumble Bee Gobies. However, Kopix Nation's (a member of this forum) new F8 nipped the fin of her BBG. My F8s ignored the 2 Gold Barbs that I used to cycle my tank with. All their fins are intact when I moved them into my 20G freshwater before raising the 29G's SG to 1.004. I guess each puffer has their own personalities.
2) Heavily planted tank and/or rock formation, landscape, etc for hiding and breaking the line of sight during a puffer fight. If using live plant, use the one that can withstand salt and grazing.
3) Heavy filtering a must.
4) For teeth maintenance, feed snails, ghost shrimps, etc. Some members use cut up shrimps (with shells) , clams (shells opened), and mussels (shells opened). So far I have only fed my F8s snails and ghost shrimps but they have been keeping puffers longer than I do so I think all of the above will work.
5) Figure 8s prefer salinity from SG 1.005 low to SG 1.008 high. My tank is currently at SG 1.004 and I will continue to bring it up until it reaches SG 1.006. If the fish store you are buying from keeps the F8s in freshwater, bring your tank up by 0.001 to 0.002 per week with water changes. The puffers might not respond well to high increase of salinity in a short period of time.
6) I found out different brand of marine salt mix might have different salt contents while discussing salt usage with Pufferpunk. Use a refractometer for measurement to be sure. Most hydrometers only measure SG from 1.010 and up. Even for the ones that measure from 1.000, people said they are not particularly accurate at low ranges.
7) Keep a bottle of Melafix handy. One of my F8s developed an cloudy eye the second day when I put him in my freshwater tank. I increased the SG to 1.002 and added Melafix. The eye was cleared in 2 days. I kept the treatment running for 7 days as directed because my other F8s have damaged fins. It helped with the damaged fins too.
I can only think of these at the moment. I'm sure someone will correct/add to my comments.
