How do deep sea fish get oxygen?

I’m cringing right now because you’re going to get blasted for saying “fishes”. lol
Aren’t there oxygen bubbles in the water or something?

As I understand it, oxygen is plentiful, except for a layer called the oxygen minimum zone, where oxygen is scarce. Not all animals can survive in the oxygen minimum zone. The ones that do, like the vampire squid, are adapted to conserve energy.

So the marine organisms that can conserve energy, they don’t need oxygen? If they do, how do they get it? And if there is oxygen in the water, why do the fish come to the surface for air?

@Eggie no, the vampire squid needs oxygen, just like most animals. But it conserves energy really well, so it doesn’t need a lot of oxygen. So it can survive in a low-oxygen area.

I’m not sure what you mean about fish coming to the surface for air.

I would guess a combination of high efficiency and low metabolism.

Deep sea fish

In the first place, “fishes” is the correct form for the plural of “fish”.

Second, and to answer the question, fishes don’t “breathe” oxygen, although like most fauna (not all) they require oxygen to live. They extract it with their gills, where their blood extracts it from the water directly. Almost all water (fresh and salt water) contains dissolved oxygen in some concentration. In fact, because of the extreme high pressure of deep water, the oxygen may be even more dense at some deep depths than it is closer to the surface. (I don’t know this for sure, and I could be wrong. I don’t study the topic.)

But fishes do not “breath” (respire) in the way that sea mammals such as whales and dolphins do, or amphibious animals such as turtles and crocodiles. They use their gills, and they do not rely upon “air” to breathe.

Lobsters and scallops, for example (and shrimp, too, and many varieties of clams) never come to the surface for air. They all have respiration mechanisms that extract the oxygen they need directly from the water.

@CWOTUS Thanks for the answer, but I said that fish would come to the surface for oxygen because I saw my aquarium fish come to the surface occasionally for air. Also, on that topic, could crabs also survive without coming to the surface?

^ Fish who gulp air are known as labyrinth fish and are a specialized group (they don’t have lungs, but a special organ for dealing with low oxygen environments).

Crabs also use gills, and do not require “air” as long as the water is sufficiently oxygenated.

Just because your aquarium fish come to the surface occasionally and expose themselves to some air does not necessarily mean that “they come to the surface for air”. Apparently, some do. Thanks, @syz, I hadn’t known that. (In any case, the question was about “deep sea fishes”, which was what I responded to.)

Water containing hydrogen & oxygen i.e H2O, so water is the only source of oxygen to the fish.