Swimming Decorator crab

Some fish facts:
The best way to keep an animal like a fish healthy is to know how it makes it's living.
We are after all very distant relatives of fish (if you believe Darwin) so we should have some sort of understanding of the way they feel.
We don’t see the way fish see, we don’t feel the way fish feel, and we also don’t eat the way fish eat. Fish don’t have tongues and they don’t "really" chew. (Try chewing without using your tongue) They bite a piece of food, then spit out smaller pieces and bite them again until they can get the food small enough so they can swallow it. Humans, as air breathing animals living on a flat surface only have to be concerned about going forward, backward and from side to side. Fish on the other hand add to that up and down. That “up and down” movement not only comes into play while swimming around aimlessly but also hunting and being hunted. At a moments notice a fish must determine which way to go to evade a predator. It has many choices and its tiny brain determines this effortlessly.
Fish can use a number of fins to swim with and they also have two means of buoyancy control. A fish’s liver is full of oil, oil floats and allows the fish to be just slightly heavier then water. Without its liver a fish would sink. Most fish also have a swim bladder so that they can become neutrally buoyant, that’s why a fish like a clownfish can remain perfectly motionless in the water without using its fins. A fish can control the volume of air in it’s bladder to a certain extent and some fish like freshwater lungfish and beta’s can use it to breathe.
Sharks do not have a swim bladder and must keep swimming to remain afloat, but a shark has a huge liver that could be ¼ of its weight, this is full of oil for buoyancy. A shark also lacks any bones so it is lighter than a bony fish.
Fish also can “feel” things from a distance. Some call this “remote feel” or “remote senses”. All real fish have a thin line starting from their head and running down their sides to their tail. This “lateral line” is directly connected to a fish’s brain and allows the fish to “feel” objects all around and even behind it. That’s why it is difficult to catch a fish with a net, even with the lights out. Most fish can feel the “echo” of water pressure bouncing off an object similar to how sonar works and many fish can sense the electric field created by the mussels of other animals. Sharks are experts at this and hammer head shark, with the large sensory organ across their wide head are the masters.
If you notice, fish never crash into the glass walls of their tank, even in total darkness.
And from the angle fish are viewing the glass; they can’t see it because they can see right through it just as we can see in from the outside.
Large schools of fish like sardines can swim fractions of an inch from each other while turning and twisting in unison, and they can do this without looking at their neighbor.
Many of the fish we commonly keep can dive into a coral head without getting a scratch and some fish can hunt in complete darkness. If a fish loses an eye, it barely notices this would be disability and gets on with its life like nothing happened.
Some fish have no eyes and get along just fine.
Fish also have no real noses but they detect odors better than we do and they can tell where the origin of those odors are even in a tank with the water swirling around them or in the sea with the tides and waves.
If you put food in a tank, the fish immediately know where it is. Crustaceans can find the food even sooner due to their even better detection systems.
These are just some things to think about as we check out our fish. They are perfectly suited to their surroundings, much better than we are.
I just thought some here would find this interesting as these are things that keep me up at night.

References:
Me