After all, fish are the reason you’re here right? I’m assuming you found this site because you’re interested in starting an aquarium, or maybe you already have an aquarium and just want some aquarium tips to help you out. I’m also guessing that the majority of people out there with an aquarium are trying to keep at least one species of fish. More detailed posts on different species of fish will be published here in the future, but for now..the basics without regurgitating everything from Wikipedia.

The Whale Shark is the biggest fish in the world. I don’t think any home aquarium hobbyist is going to be able to keep one of those any time soon, but realize that I said biggest FISH in the world. It is not a whale, a mammal, but a cartilaginous shark with gills and fins for limbs. In general, this is the type of animal we’re concerned with when talking about fish. They have skeletons made of either bone or cartilage, gills, and fins.

Cuttlefish, jellyfish, starfish, and crayfish can be kept in your home aquarium, but are not actually considered to be “fish”. Cuttlefish are cephalopods or molluscs, starfish are echinoderms, and jellyfish are cnidarians. Is that enough of the scientific names for you?

What we’re mainly going to deal with here are the smaller tropical fish that are able to be kept in the freshwater and saltwater tanks that you typically have in your home. These are fish like angelfish, tangs, clownfish/anenmonefish, discus, goldfish, koi, anthias, damsels, boxfish, and the list goes on. We may deal with some smaller sharks and rays, but we’re going to start with the fish anatomy diagram below.

Fish Anatomy:

Different species of fish have different traits and uses for many of their fins and parts of their anatomy. Some, like groupers, have a thick, muscular caudal peduncle with a large caudal fin that they use to ambush their prey. Some, like the crevalle jack, are very sleek with a thinner caudal peduncle and are made for speed. Some, like the boxfish, use their fluttering pectoral fins to swim instead of moving their caudal fins back and forth. There are more than 30,000 species of fish. With such diversity, each fish species has developed many different shapes, sizes, and uses for their fins, eyes, mouth, and all of their anatomy so that they can adapt to their environment and survive for the last 500 million years. Take a look at your fish. What fins do they propel themselves with? How big are there eyes and where are they located? How big is the mouth and how is it oriented? What are the teeth like? Can they crush coral and shells like a triggerfish?

Most fish also have extraordinary sense organs. Their vision is usually just as good, if not better, than human vision. So yes, they can see you, and most daylight fish even see colors. They also use their chemoreceptors for extraordinary senses of taste and smell. As far as hearing goes, they do have ears, but their hearing may not really be that good. I guess that depends on what you call hearing. After all, hearing for humans is actually the translation and interpretation of vibrations at different wavelengths. For this, fish have sensitive receptors along both sides of their body called the lateral line that detects the most subtle of vibrations, currents, and the motion of other fish, predators and prey.

The great thing about some of these fish that we like to keep in our aquariums is that they come in so many exotic shapes, sizes, and colors. Those colors usually serve a purpose in their natural environment. Like anglerfish, that use their color, unique anatomy, and unusual appearance to camouflage itself from predators and prey. Its predators don’t know its there so it doesn’t hunt it, but neither does its prey, allowing the anglerfish to wait until its prey unknowingly swims right in front of it. It will even use its angler like a piece of bait. There’s also the square-spot anthias. If it has a square, it is male, and that male will even change color when in nuptial display.

Finally, we want to collect and keep these fish because of their vast diversity and beautiful colors, but please do so with conservation, learning, and teaching in mind. Many marine are harvested from the ocean reefs, and this impacts the ocean reefs that they came from. We just ask that you first check to see if you can purchase a tank bred version of the type of fish that you want to keep. Tank bred fish used to be very expensive, but recent advancements in marineculture and fish farming, it is now possible to breed and rear many species of fish such as the clownfish, dottybacks, gobies, and angelfish. These days majority of freshwater fish that are available for the home aquarium are bred in tanks. Tank bred fish are also hardier and easier to keep. They haven’t been stressed by being taken from their reef home in Indonesia and transported half way around the world. They adjust more quickly to the conditions and are fully accustomed to aquarium life. After all, that is where they were born, and the only conditions that they have ever known. This will greatly reduce the chances of infection and disease.

We’re not saying that you shouldn’t keep a marine aquarium because or that you must always purchase tank bred fish, but do a little homework about the fish store that you are buying from. Make sure that they sell fish that are sustainably collected and/or aquacultured. Make sure that the store has some sort of sustainability mandate, have a guarantee policy for their fish, and are involved in ocean conservation. Ask them where their fish are from, how they are collected, and if they are tank-bred. The salesperson at your fish store should be knowledgeable to answer all of these questions, and if not, then find another place to buy your fish. A great place that I have found to purchase fish is  They have a sustainable mandate and a 15 day Live Guarantee.

One last thing about fish conservation and that’s just to keep your fish alive. If you have the patience, take your time, and keep your fish alive and happy, then you won’t constantly be heading to the fish store to buy another one. You will be keeping more fish in the store for other aquarium hobbyists to enjoy or on the reef where they belong.