If you think that's bad...
Earlier on, I started out a horrifically brief adventure.
...So I spawned right next to a river with a high swimming skill, after hearing of people getting really good combat skills by killing fish.
I was skeptical, but it seemed plausable.. If I missed crocodiles, and the such.
First I encountered a couple of MilkfishI think!, killed one, but one got away. This built me up somewhat, seeing that I could kill fish and they'd try to fight back somewhat.
Continuing on down this river, I meet a heard of Hippos. This terrified me, as I have already met Hippos in Fortress mode... They all fled down stream, thankfully. Except one.
So, with a Hippo swimming right towards me, I figure I'd best put faith in my sword and call it quits if I fail...
...
Killed it within a couple of steps. Slit throat. This made me think that actually, in a river, nothing could stop me.
How wrong I was.
I walked forwards for two squares, and I noticed a fish swimming towards me. I look at the fish... It's a Carp. This amused me, since I'd heard about dwarves dying from just seeing these, but after killing a hippo with such ease, one little fish couldn't possibly do any harm.
A few steps later, I was dead.
Didn't save any screenshots of my death unfortunately, but I think it bit strait through my skull.
The moral of the story is, Stay the hell away from water!
If you can't swim, the banks'll get you.. If you can... Then look out for that carp!