For fast cooking meats, like steaks and tender roasts, the final temperature is the determiner of how well done the cut is because the doneness is directly related to which proteins have denatured. As the temperature increases, more of the several types of proteins have been effected. This process concludes around 165 F / 74 C when the meat is well done.
All low and slow dishes, whether braised, barbecued, or slow roasted are cooked well past the point of being well done.
Therefore, the internal temperature is less a guide to how well done they are and what the final texture is like.
These types of slow cooked high connective tissue cuts like beef chuck or pork butt require time at temperature because the conversion of the collagen to gelatin takes place over time, with the process proceeding more quickly the higher the temperature.
For large cuts done very with dry barbecue methods, this could take 12 to 18 hours; for smaller cuts done in the oven or braising which achieves a higher temperature, it could take only 3 or 4. The size of the pieces also matters, as it takes time to heat the pieces through to the center, which is why stews where the meat is cut into chunks can be done in only a couple of hours.
The very best test for doneness when doing low and slow cooking is therefore to check the texture directly. Try cutting the meat, or pulling it apart. If it is not yet as tender as you desire, continue the cooking.
That said, you may find that the final internal temperature when done to your liking has risen as high as 200 F / 93 C or so but this is not necessarily so.
See also:
Recipes for fruitcake vary tremendously, without more information there isn't any way to say how long and at what temperature. I looked at several recipes, and none called for a bain marie, but some do recommend a pan of water below the cake to provide moist heat.
You might find this Food Network Recipe helpful, because it gives directions for various cake sizes, but the directions are for this particular recipe, not yours. If I were using that link as a guide, I would use a temp of about 260-265F and start testing the cakes for doneness at about 1.5 hours.
All of the fruitcake recipes I looked at use a skewer or toothpick stuck in the center to test for doneness. The cake is done when the toothpick comes out clean.
Best Answer
[In preview: ...whether baking or broiling the doneness of the fish is not determined by knowing or measuring inside temperatures. And since the broiling method just means as high as your broiler will go, the only setting one needs knowledge of, (and that for baking), is 450°F or 230°C. The other takeaway is that it is arguable whether one should even attempt broiling whole fish, at least of any real size, in a kitchen oven.]
as for baking
In his book The Science of Cooking, Peter Barham reiterates a distinction made by Rick Stein in his book Fruits of the Sea. When it comes to how one should think of "baking", at least as it applies to fish fillets and whole fish, he divides baking into a pair of subcategories denoted baking and roasting.
Of baking he says, (my brackets),
Of roasting he says, (my brackets, my bolds),
and to which he adds, (my bolds),
So as touches the reliability of method, the form of baking which calls for the lower temperatures plainly offers up up greater reliability for cooks with less experience baking fish, (And by less experience, I really do only mean as compared to persons with more experience), while the form of baking which calls for the higher temperatures is the only baking option or large, whole fish.
Therefore, if to choose the baking method, (or in Barham's language roasting), "internal temperature does not need to be measured per se but is more than adequately accounted for (gauranteed correct) by the exterior condition of the fish (crispiness) and moistness of the fish (when pressed down on) at the end of its cooking cycle. Thus it can be said for purposes of baking a whole fish, irrespective of size (within reason), the oven temperature should be set at 450°F (230°C).
There are however other important qualifiers which will be spoken to shortly. But first let us turn our attention to what Barham has to say about broiling fish.
as for broiling
On broiling, which he refers to as grilling, Barham has several things to say. Most generally he calls it,
He goes on to explain, (my parenthetical),
From here, he goes on to make a case for using a blowtorch on whole fish rather than a conventional grill (broiler), moving the torch constantly over the fish in sweeping motions, the essence of which can be summarized by this extraction,
So unless one has access to a professional-grade, super high heat producing commercial oven, Barham plainly would have us to abandon even considering putting a fish under our broiler at home, especially a large fish.
Certainly however there is at least the appearance of disagreement as to the merits of so severe a stance. I say appearance, because professional advice given to professionals implies use of professional-grade equipment, and so should probably not be applied too broadly. Wayne Gisslen in his Essentials of Professional Cooking has the following (among many) points of advisement for broiling fish which, it must be reiterated, may or may not work with a standard kitchen stove,
Gauging by the language he employs, it is interesting to note that Gisslen is not thinking of fish here in terms of overall weight so much as he's thinking of it in terms of thickness.
broader considerations
For a moment of synopsis: If to rely on the above considerations, whether baking or broiling the doneness of the fish is not determined by knowing or measuring inside temperatures. And since the broiling method just means as high as your broiler will go, the only setting one needs knowledge of, (and that for baking), is 450°F or 230°C. The other takeaway is that it is arguable whether one should even attempt broiling whole fish, at least of any real size, in a kitchen oven.
Beyond these limitations, in her book The Fishmonger's Apprentice, columnist and author Aliza Green echoes some standardized considerations, or matters of practice, when dealing with fish one intends to prepare, a couple of which are as follows, selected specifically because they involve the use of snapper.