How to ID Reef Fish

Fish can be easy to identify if you know what to look for. Just like any plant or animal, we need to understand what features some fish have in common, and what the differences are.

When identifying a fish, there are several things that you should be looking for. Here are some tips when observing a fish. You can check your fish online on FishBase or use the many Fish ID books that you can buy in bookstores.

Things to look at are:

1. Anatomy

a. Tails – Sometimes called caudal fin helps fish to propel forward through water. Fast swimming fish have forked fins. Rounded rails are usually found on slow moving fish but they are capable to provide short burst of speed.

b. Mouth – Location of the mouth on a fish can tell you how and what it eats. Mouth located on the upper front means the fish is a surface-feeder. Mouth located on the middle front means the fish finds food in front of them. Some fish (goatfish) have barbells to help them find prey in the sand. Butterflyfish have small pointed mouth that specializes in getting into small crevices to find food.

c. Shape – General shape of the body will help you identifying a fish.

2. Colors and markings

Most reef fishes are colorful, making it easy to use colors to identify them. But relying on colors alone is not enough to make identification. It is important to also note the markings on the fish. Look at the diagram below to familiarize yourself with the terms used in fish ID books.

3. Habitat

Sometimes the location of the fish will give you clue as to what kind of fish it is. Grouper likes to perch on the bottom of the reef waiting for preys. A groupers mouth is located in the upper front, meaning they will catch prey swimming above them. Goatfish usually swims in sandy area where they can use their barbells to find preys.

Most of the time, i will bring a slateboard with me when I go snorkeling to draw fishes or any other marine organisms that I want to identify later. So next time you head out for a snorkeling adventure, be sure to bring your slateboard, pencil and an ID book to identify your fish.

Sal’s tip: Be sure your hands are dry before you touch your ID books :) Don’t want to ruin it.

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