About Fish

Fish as pets, fish as food, and fish as sport make this collection of wildlife one of the most popular in the world.  As members of the animal kingdom’s order Osteichthyes and belonging to the diverse family of aquatic creatures, fish are renowned for their grace, adaptability, and vibrant colors.

Let’s dive under together and explore the world of fish, looking at their various species, popular types, size variations, feeding habits, reproduction, lifespan, unique characteristics, and the remarkable features that set them apart from other creatures.  Let’s embark on an exciting underwater journey to discover more about these fascinating inhabitants of our planet’s waterways!

Types of Fish:

With over 33,000 identified species, fish exhibit an astonishing range of diversity and adaptations. Whether as pets or part of desired cuisine, some of the more popular types of fish found worldwide include bass, catfish, salmon, tuna, angelfish, goldfish, clownfish, pufferfish, and mahi-mahi.  Each species possesses its own unique features, habitats, and behavioral patterns. 

Here is a quick glimpse into some of the more popular types of fish:

Bass: Bass are popular freshwater fish known for their agility and voracious appetites. They have a streamlined body, sharp teeth, and are found in various regions around the world. Bass are prized by anglers for their sport fishing qualities.

Catfish: Catfish are bottom-dwelling fish characterized by their whisker-like barbels and scaleless bodies. They inhabit both freshwater and saltwater environments and are renowned for their excellent sense of taste and smell.

Salmon: Salmon are anadromous fish, meaning they spend part of their lives in freshwater and part in saltwater. They are famous for their impressive migrations, returning to their freshwater birthplaces to spawn. Salmon are prized for their delicious flesh and are highly valued in the culinary world.

Tuna: Tuna are large, fast-swimming fish found in both tropical and temperate oceans. They possess streamlined bodies, enabling them to reach remarkable speeds. Tuna are highly sought-after for their meat, and they play a vital ecological role in marine ecosystems.

Angelfish: Angelfish are colorful, tropical freshwater fish known for their distinctive shape and striking patterns. They are popular in aquariums and are admired for their elegance and beauty.

Goldfish: Goldfish are ornamental fish that have been selectively bred for their vibrant colors and unique forms. They are commonly kept as pets in aquariums and are known for their graceful swimming and long lifespan.

Clownfish: Clownfish are small, brightly colored fish known for their symbiotic relationship with sea anemones. They reside in the warm waters of the Indian and Pacific Oceans and are famous for their role in the animated film “Finding Nemo.”

Pufferfish: Pufferfish, also known as blowfish, possess the remarkable ability to inflate their bodies when threatened, deterring potential predators. They come in various sizes and are found in both freshwater and marine environments.

Mahi-Mahi: Mahi-mahi, also known as dolphinfish, are large, vibrant fish inhabiting tropical and subtropical waters. They are renowned for their striking colors and acrobatic displays, making them popular targets for sport fishing.

Unique Characteristics of Fish:

Fish possess an array of unique features and adaptations. These include gills for breathing underwater, streamlined bodies for efficient swimming, scales for protection, lateral lines to detect movement and vibrations in the water, and swim bladders for buoyancy control. Fish also display a stunning array of colors, patterns, and behaviors that enhance their survival and reproductive success.


The mesmerizing world of fish captivates us with its beauty, diversity, and remarkable adaptations. From the graceful movements of the angelfish to the astonishing migrations of salmon, each fish species contributes to the delicate balance of our aquatic ecosystems. 

By understanding the various types of fish, their feeding habits, reproduction, lifespan, and unique characteristics, we gain a deeper appreciation for these enchanting creatures.

Let us cherish and protect our underwater companions, ensuring the conservation of their habitats and the preservation of their vital role in our planet’s biodiversity.

Types of Fish

Albacore Tuna

The Albacore Tuna, a highly migratory fish, is prized for its mild-flavored, firm flesh. It's known for its streamlined body and long pectoral fins, making it a popular catch.


Angelfish are colorful, disc-shaped tropical fish known for their striking appearance and fin extensions. They come in various species, each with unique patterns & colors.


Anglerfish, with their bizarre appearance and unique hunting method, these deep-sea predators use a bioluminescent lure to attract prey.


Anthias are vibrant reef fish known for their stunning colors and social behavior. They live in coral reefs, forming schools and adding beauty to underwater ecosystems.


Barracudas are sleek, predatory fish found in warm ocean waters. Known for their sharp teeth and fast swimming, they are apex predators.


Bass are freshwater fish known for their diverse species, including largemouth and smallmouth bass. They are popular among anglers as a food source.

Blue Tang

The Blue Tang, known for its vibrant blue coloration and prominent caudal spine, is a reef-dwelling surgeonfish found in tropical waters.


Catfish are a diverse group of freshwater and saltwater fish known for their barbels and adaptability. They inhabit various aquatic ecosystems.


Cichlids are a family of diverse, colorful freshwater fish known for their parental care and territorial behavior. They are popular in the aquarium trade & research.


Clownfish are small, brightly colored saltwater fish found in the Indo-Pacific, known for their symbiotic relationship with sea anemones & are popular in aquariums.


Discus fish, native to the Amazon River basin, are known for their vibrant colors and round shape. They are popular for their striking appearance.

Emperor Angelfish

The Emperor Angelfish is a stunning species with vibrant blue and yellow stripes. It's prized for its beauty and often seen in saltwater aquariums.


Flounders are flatfish known for its camouflaging abilities, with both eyes on one side of their body and a mottled appearance blending into the area.


Gars are long & slender fish with sharp-toothed jaws, known for their primitive appearance. Often found in freshwater habitats across N. America.


Glofish are genetically modified zebrafish that fluoresce under ultraviolet light, coming in vibrant colors like red, green, & orange, enhancing aquariums.


Goldfish are a popular freshwater fish known for their bright colors and unique appearance. They make great pets in aquariums and ponds.


Groupers are large, predatory fish found in warm seas. They have stout bodies & are known for their strength, making them a prized catch for anglers.


Guppies are small, colorful freshwater fish popular in home aquariums. Males are known for their vibrant colors and long fins.


Halibut is a large, flat-bodied fish found in both the Atlantic and Pacific oceans. It's known for its delicious white flesh and is a popular seafood choice.

Jackknife Fish

The jackknife fish is a small, tropical species known for its distinct black & white coloration & sharp-edged body. It inhabits coral reefs as a nocturnal feeder.


Koi, a colorful variety of common carp, are popular ornamental fish in ponds and gardens. They come in various vibrant colors and patterns.


Lampreys are jawless fish with toothed, funnel-like mouths. Some are parasitic, attaching to other fish and sucking blood, while others are filter feeders.


Lionfish are strikingly beautiful but invasive predators known for their venomous spines. Native to the Indo-Pacific, they have become a concern elsewhere.


The Mandarin Fish, also known as the Mandarin Dragonet, is a colorful reef fish found in the Indo-Pacific, known for its colors.

Moorish Idol

The Moorish Idol is a vibrant fish with a unique appearance, often seen in tropical coral reefs. Its long, slender body and bold colors make it a favorite.


The Oscar fish, also known as the tiger Oscar, is a popular and colorful freshwater species known for its distinctive patterns and active behavior.

Parrot Fish

Parrotfish are vibrant species known for their parrot-like beaks and ability to transform coral into fine sand, playing a crucial role in reef ecosystems.


Piranhas are carnivorous freshwater fish found in S. America. Known for their sharp teeth and group hunting behavior, they are formidable predators.


Pufferfish, also known as blowfish, are unique fish known for their ability to inflate into a ball-like shape as a defense mechanism and their potentially toxic flesh.

Rainbow Trout

Rainbow trout, native to N. America, are popular fish known for their vibrant colors, including a pink stripe along their sides, and excellent taste when cooked.

Red Snapper

Red snapper is a saltwater fish, famed for its vibrant reddish hue, sharp teeth, and delicious flesh. It's a popular catch among anglers and seafood enthusiasts.


Rockfish are a diverse group of colorful marine fish known for their spines and vibrant patterns. They inhabit rocky coastal areas and are popular in seafood cuisine.


Sailfish are large predatory fish known for their distinctive sail-like dorsal fins & remarkable speed. They are prized catches due to their agility & striking appearance.


Salmon are migratory fish famous for their determination to return to their birthplace to spawn. They are prized for their delicious taste.

Betta Fish

Betta Fish, also known as Siamese Fighting Fish, are vibrant, aggressive, & beautifully colored fish popular for their striking appearance & unique behavior.


Sturgeons are ancient, large, and long-lived fish known for their unique, bony plates and prized caviar. They inhabit freshwater and are essential to aquatic ecosystems.


Swordfish are large predatory fish with a distinctive, elongated bill resembling a sword. They are fast swimmers found in warm oceanic waters.


Swordtails are fish known for their vibrant colors & distinct sword-like tails. They are popular in aquariums & come in various species and color variations.

Tiger Fish

Tiger fish are fierce predators found in African rivers. Known for their striking appearance and sharp teeth, they are prized for their challenging sport.


Tilapia are versatile fish popular in aquaculture. They have mild white flesh and are farmed worldwide for their taste & adaptability to various cooking styles.

Trigger Fish

Triggerfish are colorful fish known for their unique appearance and strong jaws. They inhabit coral reefs and are admired for their vibrant colors and distinctive spines.


Tuna are swift, powerful oceanic fish highly sought after in the fishing industry. They're known for their streamlined bodies and are a popular choice for seafood.


1. What are the largest and smallest fish in the world?

The largest fish in the world is the magnificent whale shark, which can reach lengths of up to 40 feet (12 meters) or more. Other large fish include the swordfish, sail fish, marlin, and sturgeon.

On the other end of the scale, the world’s smallest fish is the Paedocypris progenetica, measuring just 0.3 inches (7.9 millimeters) in length.

2. What do fish eat?

Fish exhibit a wide range of feeding habits depending on their species and ecological niche. Some are herbivorous, feeding primarily on plants and algae, while others are carnivorous or omnivorous, consuming other fish, invertebrates, or a combination of both.

Different types of fish have specialized adaptations for capturing and consuming their prey, including sharp teeth, suction feeding, or filter-feeding mechanisms.

3. How do fish reproduce (Life Cycle)?

Fish employ various reproductive strategies. Many fish species engage in external fertilization, where females release eggs into the water, and males simultaneously release sperm to fertilize them. Some fish build nests or use natural structures for egg deposition, while others guard their eggs and young.

4. How long do fish live? Fish Lifespan

The lifespan of fish varies greatly depending on the species. Some small fish may live only a few years, while larger species like koi fish can live for several decades. The oldest recorded fish was a Greenland shark estimated to be over 500 years old!

5. What is the difference between fish and other animals?

One key distinction between fish and other animals, such as mammals or birds, is that fish are ectothermic, meaning their body temperature is regulated by the surrounding environment. Additionally, fish respire through gills and live exclusively in aquatic environments, unlike terrestrial creatures.

  • Burnie, David & Wilson, Don, Animal, Smithsonian Institute, Washington DC.
  • Hickman et al, Integrated Principle of Zoology, McGraw Hill, Boston.