On Burning Blade, stonescale eels go for 1g a pop. Firefins and Oily Blackmouths go anywhere from 80s-2g per stack of 20. Deviates i'm not sure, as the price ALWAYS varies. Depending on the time of day (yes it does matter), you can increase your catches of Stonescale eels. I started fishing these up for skill and cash at 200 in Steemwheedle port (tanaris).
I make about 20g an hour fishing stonescale eels, which is reasonable cash. You would prob get more mining thorium or mithril, but competing with other people is also hard. If you get to fishing 300 (not all that hard, obtainable in level 1 zones), and you have a high level char, head to Azhara(sp?) Bay of Storms. Theres places in the bay where you wont get aggro. This is a great place for stonescale eels. You get a 20% drop rate. My record is about 32 in an hour. But people have told me they've gotten a 45 record. If you do start fishing stonescale eels, the best possible time is 12am-6am server time. Might suck, but your % of eels caught will be higher, making you more cash.
Fishing may be boring, but up to 32g an hour can't hurt either. Either this or running around IF throwing snowballs, i'd rather make the money. Happy fishing^^