[Chemistry4me (OP)]

Why do river fish have so many more bones than fish from the sea?
But it is not just the amount of bones, some of those river fish have jagged bones that look like tree branches! Why on earth does that happen?  [:0] As well as that, they are very very fine, which makes it even worse when you try to eat them!
But if I ate a salmon, I can be assured that I won't be picking out bones half of the time, and fighting to stay alive.
Why is this?

What do you think?

[DoctorBeaver]

Is it possible that river fish need to be stronger swimmers because they are more likely to have water currents to contend with? There was a fish I used to eat in Uganda (locally called ngege but I think it's what we call Tilapia) that had 2 spines, 1 above the other, connected by many tiny ribs.

[Phil1907]

Where do yo get the idea that the number of bones is different? The salmon you ate was probably filleted.

[MonikaS]

Or you use the trick my grandfather had: Eat fish in darkness, so you can't see the bones!

[LeeE]

Is it possible that river fish need to be stronger swimmers because they are more likely to have water currents to contend with? There was a fish I used to eat in Uganda (locally called ngege but I think it's what we call Tilapia) that had 2 spines, 1 above the other, connected by many tiny ribs.

Now that [two spines] is very interesting.  Do both of the spines carry a spinal chord?

For those people who think that Hom-Saps represent the peak of evolution; bilateral symmetry, combined with just a single spinal-column, offers hardly any resilience to unforeseen damage.  Far from being an optimal design, we're incredibly fragile.

Actually, I'd be quite surprised to find that freshwater fish have more bones that saltwater fish, and Salmon aren't really a very good example to illustrate the point though; salmon occupy both fresh and salt water at different stages of their life, and I don't think their bone-count varies.  It's the same with a number of other fish that either migrate between fresh and salt water, such as trout and eels, as well as fish that can tolerate brackish water, which is somewhere in between fresh and salt water.

Ultimately though, all vertebrate animals share the same basic skeletal design and while the bone-count does vary between species it seems to do so more on the basis of physical form rather than habitat;  long and thin animals, such as snakes and eels, will both have more ribs than shorter bodied animals, regardless of what type of vertebrate they are and what type of habitat they occupy.

[lyner]

I think that a possible reason is the greater range of sea fish species available. There are dozens of fish types that get chucked back in by sea anglers - one reason is the lack of flesh and large number of bones. They select the most popular (less bony).

[Chemistry4me (OP)]

They select the most popular (less bony).

Hmm... mayyyybe.

[Chemistry4me (OP)]

Where do yo get the idea that the number of bones is different? The salmon you ate was probably filleted.

Okay, it wasn't filleted I know that much []
But perhaps I've just caught the wrong fish and they just happened to have extra small bones that look like barbed wires!

[lyner]

I think the sample on which the original statement was based, may be a bit biased / selective - if you took fish at random from a trawl net, you might find a huge mixture of 'boninesses'.

Popular (and expensive) fish, like Sea Bass and Bream, have a very well defined skeleton and you can  just 'stroke' the flesh off it. Cheap fish like (the wonderful) mackerel have a lot of flimsy bones but they are largely crunchable  up if you are brave enough. It's well worth it to get over the initial problem.

I am now off to the fishmonger's - the idea of fish for dinner is unquenchable.

[DoctorBeaver]

I like monkfish. Ugly but very tasty.