are arowanas legal in florida?

[Oddball]

Used to be able to do that. Now, a fishing license allows you to sport fish with approved fishing tackle. Seining and dip-netting are usually not allowed for sport-fishing. There are also cast-net permits. If you're not looking for small species, this method/permit might be what you're after. However, some fishing areas don't allow nets because they rip up bottom plants. Like I said, call Donna.
It would also help searching a reading the regs/restrictions on the F&W, DNR, and sport-fishing web sites for the areas you want to collect in before calling so you'll sound more credible during the call. The process is not impossible but, it is more difficult than it was several years ago.

 

[Oddball]

and in my home town (Kiev), i have seen live clarius in supermarkets, along with live carp, trout, stergen, northern pike. i am not sure which exact species they were (they pretty large and brown)

That's nice for collectors but, not so great for the environment. Just a few decades ago, the Louisiana crayfish (P. clarkii) was imported into several countries in Europe. The american crayfish thrived but, turned out to harbor a virus the P. clarkii cray had evolved an immunity to. The virus wiped out nearly 75% of all european crayfish species. Those populations are still struggling to recover today.

 

[vitaly]

well, i am pretty sure Clarius would not survive in former Ukraine (it has a climate similar to Ohio). i think they are aquacultured indoors.
but I have read about crayfish plaque.

Ironically we are having problems with American sunfish (bluegill) and the Black Sea Pipefish. Yes, saltwater Pipefish had somehow adopted to freshwater and they are in Dnepr River now. I've tried to catch them, but i guess i went to the wrong spots and did not see them.

i guess, they would have made a good exotic fish