As far as xp rates go, you should be getting 40-50k if you drop. If you alch you should except far higher. I don't think I can give you exact numbers because my rates are faster than yours (since I'm a much higher fishing level) and I don't really do it with 100% attention, but if you google barbarian alch-fishing that'll give you some pretty reliable rates and detailed guides/videos. Be sure to buy fishing bait of the GE to use. Don't bother cutting the fish. That is NEVER worth it. EDIT: Remember to use decorated fishing urns and your best fishing familiar. Always worth it. Buy the urns if you don't feel like making them and add water runes. I personally also recommend summoning potions rather than running north to use the summoning obelisk. If you are alch-fishing, you don't need to worry about inventory space at all, as long as you have 3 spaces or so free, so feel free to fill up your inventory with as many urns/pots/pouches that will last you.