Sturgeons are basically underwater rhinoceroses. They're rated at 1,5 m³ (when adult), which for a fish means roughly one and a half tons. Wikipedia says there's been a record sturgeon of this size a few centuries ago, but typically a really big one will weigh about 300kg, a bit heavier than a tiger.
I run into 'surprise, you're dead' moments way too often:
The dwarf kicks you in the hand, shattering the bone through the bismuth bronze gauntlet - you are deceased.
Sneaking up to a sturgeon: You have been spotted! - You are deceased.
And recently: You throw the monitor lizard! - You are deceased.
Yes, there are messages in between, but in all cases it was basically something goes wrong - bang dead, no input taken in between.
The monitor lizard was actually quite hilarious - apparently, throwing drops the creature on a random spot within range, and if it lands on your spot (and you have dodging turned off), it's basically you getting hit in the face with a large falling object.
And not my death, but that of all my twelve companions - sleeping in the wilderness, got jumped upon by a gang of twenty bandits, and my entire party groggy from waking up. I got away of course and got another (eighteen!) mercenaries and got my revenge - the damn stupid bandits tried to ambush us again, but this time during the day. Using companions to handle bandit camps really is a tricky business, the higher level bandits have ridiculously large groups, complete with a handful of weaponmasters, and since your companions attack with the tried and proven (to be disastrous) dwarven suicide charge, the defenders have an immense tactical advantage. Handling a roc with all of five companions left was a picknick by comparison.