Freshwater

Anabantids can develop diseases brought on by crowded tanks with bad
water conditions, just like other species. Take our word for it, they’ll be
healthier and happier in a proper aquarium. (Anabantids should be provided
with the same high quality filtration, heating, and other proper conditions as
is standard with other tropical fish.) They will like you a lot better too.
The Senses
Like humans, fishes have five senses: taste, sight, hearing, touch, and smell.
Fish use all these senses to locate food, communicate with one another,
attract mates, and avoid bigger and meaner fish. Fish have been known to
learn to do without one or more of their senses when they’re injured or born
with a physical defect. We’ve seen fish in the worst possible physical condition
continue to survive. Think how great they can look and feel if we keep
them in the best possible condition!
Sight
Here are some fun facts about fish eyes:
Chapter 7: Fish Anatomy
Most fish have the ability to see in two directions at the same time. This
physical phenomenon is known as monocular vision.
Fish can’t completely focus both their eyes on a single object at the
same time.
Fish do not have eyelids and sleep with their eyes wide open, resting in
a hypnotic state.
Most fish are nearsighted and see clearly only about a foot away. So, if
you stand across the room, smiling and wildly waving both your hands
to entertain your fish, don’t hold your breath waiting for them to
respond.
The lateral line system
Fish have an interesting system known as the lateral line, which helps them
locate objects in their path and in their surrounding environment that they
cannot see normally due to their limited eyesight (see Figure 7-2). This line is
incomplete in some species. The blindcave fish use this system to navigate,
and killfish use it to help locate insects above the surface of the water.
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