Someone said in alt.games.warcraft that their alt could do the baby croc quest (I assume level 70) even though that alt hadn't fished before, getting their skill from 1 to 20 doing that quest, so there's no fishing skill minimum.
There is still an invisible wall preventing swimmers from reaching Sunwell Isle; this might be worth mentioning to any below-70 fishers thinking of going there. I don't know if players below 70 will be able to use the portal to Sunwell Isle that will spawn in Shattrath after the required number of Sunwell dailies are completed by players in the realm.
