Okay, don't take this the wrong way, but the 400L maybe just a tad bit too small for a fahaka in the long run, since the recommended min. tank size is normally 450L. So depending on the dimensions of the tank you maybe better choosing a slightly larger tank, say a 450L+ or possibly choosing a smaller puffer such as an Abei, or even a group of SAP's, although the dentistry may be tricky with a large group of them. Alternatively, if you don't mind the lurking species of puffers, you could always consider getting a pair of suvattii's.
As for your question on live shell fish, normally if you are literally buying shell fish that is live from the market, people would soak them in water until they open up so that any of the gunk that is inside comes out and then rinse them off and freeze for 10 days to kill of any parasites etc. Although i personally tend to buy mussels and scallops already frozen, which i then defrost in a cup of tank water and feed. but sadly since i live in Hong Kong, i can't tell you where would be the cheapest place to pick up sea-food in your area?
Lastly, as for getting rid of algae, its sadly going to take manual labor, now although i'll admit i've never owned a fahaka myself, i do have a very unpredictable palembang, and one of the tricks i've read on here is to have a divider made up either from an egg crate or acrylic to basically build a temporary wall in the tank so that your fahaka can be on one side, while you work safely on the other side of the tank, then once you've done one side, just usher him to the other side and repeat...
But i'm sure some of the fahaka owners on here will probably be able to give you better advice so just hang out and see what they have to say...
Oh and btw
![[welcome]](./images/smilies/welcome.gif "welcome")
Sleep is the cousin of Death...
Looking at getting a puffer of at least 6 to 8 inches + I posted in the brackish section a while a go about a GSP but didnt want to go down the marine route. Really would like to stay FW. I have my eye on a RENA600 that someone is needing to part with by the end of summer. Really considering a Fahaka. The only question is about food, well live food really not interested in feeder fish due to health reasons for the puff, but live shell fish where do you guys get them from is there still a risk of desease with these not being frozen. Any advice would be appreciated
I should've aimed that at the poster really