Another vote here for just frying your fish in less oil.  

When I get done frying up my fish...whether it be for 1 person, 2 people, or 8 people...there's rarely more than a tablespoon or two of oil left in my pan and that's full of seasoning that I may or may not want next time I cook fish.

If you are having trouble with the concept of cooking fish adequately with very little oil it may be helpful to realize the physics behind cooking with oil and the effect volume of oil has on results.

Oil has 2 main functions.  It's a heat equalizer and a way to "store" heat.  

It functions as a heat equalizer by making the temperature of your pan more uniform regardless of where or how concentrated your heat source is.  The better your pan is at distributing heat on it's own, the less oil you will need.  A quality frying pan usually takes up the same amount of room in your pack, but it does weigh more.  You want to find the sweet spot on the spectrum of weight where you aren't lugging several pounds of cast iron but neither are you carrying an ultralight pan that gets hot only where the stove flame directly contacts it.  If you have a reasonably decent pan, just a thin layer of oil is needed to evenly cook the bottom side of any fillet, no matter how thick.  Fill your pan with fillets and the oil travels higher up the side of each of them.  No need to submerge or even get halfway up the fillet.  The fillet cooks from the bottom far more and far faster than it does from the sides.

Oil also functions as storage for heat.  Generally on a canoe trip, this is a function of oil that is rather unneccesary.  The reason why restaurants use deep fryers that hold a ton of oil is that they need to be able to cook large volumes of (often frozen) food as quickly as possible.  A large pot of oil stores enough heat so that when a basket of frozen goodies goes in it, the temperature doesn't dive down below the point where the food will cook properly.  It also mitigates the fact that the pot that the oil is contained in is a poor distributor of heat.  Granted, if you are feeding an army on a canoe trip (6-8 people) there is some advantage to using a high-volume frypan with a lot of oil...your fillets will cook faster.  But for 1-4 people, you can generally cook fast enough that the tradeoff of having less weight (smaller, lighter pan and less oil) is worth the minimal extra cooking time.

All that said, if you are cooking battered fish, you'll need more oil.  In this case, you have to get the oil level at least 2/3 of the way up the thickest fillets or you will have doughy batter on the edges.  With breaded fish, you have to hit the halfway mark on each fillet.  With seasoned, naked fillets as long as the bottom of the fillet is in contact with the oil, you're good.  For my money, batters and breadings are far inferior ways to flavor your fish.  Spices on naked fillets are much simpler and less heavy/bulky to lug around.