Is it kosher?
I recently went to Caviarteria in Las Vegas and had a selection of caviars from kosher fish, which included salmon roe, trout roe, and pike roe. This was the first time I ever saw pike roe. These and the whitefish rose Season brand makes that sells in most supermarkets are the only kinds of roes from kosher fish I've ever seen.
Caviarteria has a web site you can order from and locations in NYC, Las Vegas, Miami, and Beverly Hills.
In answer to your follow-up question, I read that the term caviar is supposed to apply only to eggs from sturgeon and all others are referred to as roe.