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Guide to Fish Keeping as a Hobby




a boy looking at his fish tank

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Fish keeping is a popular hobby that involves caring for pet fish in a pond or more commonly a tank. There are truly countless fish that you can add to your aquatic community, including the showy Angel Fish, the brightly colored Neon Tetra, or the more subtly colored Black Moor (a type of Goldfish). 

All it takes is the right tank size, friendly tankmates, the proper water conditions, and some regular care. Your reward will be some simple, lovable little pets that can create a living water show!

Why Keep Fish?

Fish are kept mostly for their visual appeal. These multi-colored creatures boast delicate fins and graceful movements that make them relaxing and even mesmerizing to watch. This goes doubly if you also have a beautifully decorated tank. Many also consider pet fish to be rather cute, despite the fact that they are hands-off.

What Kind of Care do Fish Require?

The Right Tank Size

Sadly, fish are often crammed into tanks that are much too small for them. This is one of the biggest reasons that they die. Why is this? Besides the claustrophobia and stress, there’s not much room for them to swim around in. 

Tanks any less than 5 gallons are also much trickier to stabilize when it comes to sensitive environmental factors like temperature, oxygen, and pH.

The size of your tank will really depend on the size of your fish, which will depend mainly on their species. 

Mosquito Fish, for example, are rarely bigger than 1-inch in size; goldfish will often grow as big as they’re allowed to (maxing out at just over 1 foot).

For one fish, a 5-gallon tank is the lowest size acceptable, and for two, a 10-gallon tank. It’s recommended that your fish tank is at least 10-15 gallons, and 20-30-gallon tanks are even better.

To get your started, here’s a handy table of a few common fish and what tank size they require (the range is due to the varying sizes subspecies breeds have, as well as the number of these fish you’ll be placing in one tank):

Type of FishNumber of Gallons Needed in the Tank
Pleco20-75 gallons
Gourami10-55 gallons
Cory Catfish10-30 gallons
Angel Fish30-55 gallons
Guppy10-20 gallons
Clownfish20-50 gallons

The Optimum Oxygen Levels

What does this require? Fish sometimes have different oxygen requirements, so pay attention to this, too.

So that your fish can breathe, you will need to provide the optimum levels of oxygen in your fish tank. You can keep an eye on the oxygen levels with an oxygen meter. To keep the water moving and oxygenated, you will need at least one, decent-quality water filter. Plants and air stones will also help to increase the oxygen level.

Greenery in the Tank

While greenery in a fish tank is not always strictly necessary, your fish will definitely appreciate it. A few nice aquatic plants can transform an empty fish tank into a little piece of home (as most fish are accustomed to lush lakes, algae-filled oceans, etc.).

Plants will also naturally aid in purifying and oxygenating your tank. They can make your fish healthier and happier. 

Just be aware that plants can require different temperature or acidity requirements, so make sure that they are compatible with your fish’s requirements and the conditions in your tank.

Following are some of the easiest-to-grow and most-beloved by fish aquatic plants that you can grow in your fish tank:

a beautiful aquarium

What are the Best Plants for a Fish Tank?

  • Java Moss. If you’re a fish keeper looking for some aquatic plant ideas for your tank, you’ve no doubt come across Java Moss. This is a classic plant that’s always worth mentioning, especially for the beginner. This water-loving plant grows in fine branches, with tiny, rounded leaves, and doubles as some truly lovely tank decor. For aspiring fish breeders, Java Moss is a favorite hiding place for fry (baby fish).
  • Coontail. Coontail, like Java Moss, is one of the easiest aquatic plants to care for. It also provides great cover for fry and helps prevent blue-green algae and generally purify the water. This aesthetic plant grows in tall, fluffy green spires, which could be considered to look like a fluffy tail (hence, the name Coontail).
  • Water Wisteria. Water Wisteria is largely popular thanks to its ability to decrease the levels of nitrates, nitrites, and ammonia in a tank. This will help your fish breathe easier while making your water filter’s task easier. It will also keep pesky blue algae at bay and has microbial properties to help keep your fish from developing diseases, too. The leafy plant is extremely useful overall and makes a fine addition to nearly any tank!
  • Dwarf Baby Tears. Dwarf Baby Tears are an aquatic plant, named for their tiny stems and leaves. It will create a soft, green carpet along the bottom of a fish tank. This is ideal for fry, and simply for fish in general to rest in comfort. Like all aquatic plants, Dwarf Baby Tears will also help to oxygenate and purify the water. 
  • Amazon Sword. The Amazon Sword is quite different from the rootless, gently attaching Java Moss plant, in that it has roots that are very long and deep growing. This calls for plenty of rich substrate (of course, make sure that the substrate is suitable for your fish, primarily). As its name implies, the Amazon Sword plant grows in tall, sword-like leaves, which double as fantastic tank decor. 
  • African Water Fern. The African Water Fern, like Java Moss, is an epiphyte. This means that it attaches gently to the surface of logs, rocks, etc., and sustains itself through photosynthesis and organic detritus in water. This aquatic plant has long, delicate leaves, and creates a lovely fish shelter.  

The Proper Lighting

Tank lights are rated in Kelvin, and range from around 5,500 and 8,000 K. While a more powerful light will make for faster-growing and brighter-colored plants, it can also promote the growth of undesirable blue algae. Some fish also prefer their tank a bit dimmer.

So, it’s recommended to first consider your fish’s preferences, then your plants, and to carefully choose the lighting in your tank.

Most fish need 2-5 watts of full spectrum light in order to thrive; in the wild, they depend equally on sunlight filtering through the water. 

Clean Water (a Water Filter)

There are many water filters to choose from, and their price varies. It’s never advisable to choose a cheap water filter. This can harm the plants and disrupt the fish’s feeding. Instead, go for a gentle, moderately priced option, like a sponge filter. 

A biological filter is also a necessity in a tank, as it turns super-harmful ammonia (from the fish’s urine) into nitrates (which are less harmful and can even be beneficial). 

The Ideal Temperature

Most fish require nice, warm water, at 70° to 80°F. This can vary somewhat according to species, as there are those that prefer it cooler (or, rarely, warmer).

The Proper pH

Fish do best with pH levels just above or barely below neutral, which is 7.0. They typically prefer somewhere between 6.8 and 7.7 pH. Some fish are especially sensitive to fluctuations in pH, and changes can cause them to suffer and even die off. So, this is something you will want to keep track of. How? An aquarium test kit will allow you to check the pH. 

You must also make occasional water changes, replacing the old with new, properly conditioned water.

A Stress-Free Environment

Perhaps surprisingly, because they are so small and simple, fish are sensitive animals. They will react to a house move with stress and may even refuse to eat for up to a week. 

Fish will also become unhappy and unhealthy in noisy environments. For example, they should never be kept in a room with a noisy TV. 

Predatory pets should also be kept well away from the tank, as they will incite fear.

a stunning petshop aquarium

Caves, Logs and Other Fish-Favored Decor (Optional)

One of the top requirements for fish is privacy. It’s important to provide this with elements like caves, logs, and other nooks in the tank. Among shy fish, private little areas such as this are key to their peace of mind and happiness overall.

Also feel free to add colorful pebbles and other little details for some whimsical decor. Just make sure that everything is nice and smooth, so it won’t scratch any of your fish, and sanitize every item properly before you put it in the tank.

What Kind of Food Should You Feed Your Fish?

What to feed your fish will depend on the types of fish you have; this is something you should consider when picking out your little fish community. Some fish, like the Cory Catfish, are bottom feeders. They require sinking pellets, which will collect along the floor of the tank. Other fish, like the Guppy, prefer flakes, which instinctually remind them of bugs and bits of algae in the water. 

Additionally, some fish are omnivores, and enjoy live foods, such as mealworms, water fleas, sludge worms, earthworms, or brine shrimp to supplement their diet. Others are herbivores and will have no such interest. 

When feeding your fish, make sure that timid feeders, like the Threadfin Rainbow fish, get enough to eat (you should see the proper portions on the food container).

So that the leftovers don’t gunk up the tank and begin to rot, clean them up immediately once the feeding is over.

What are the Best Fish for a Fish Keeper? 

1. The Corydora (Cory Catfish)

Corydoras are small, well-mannered fish that can make a lovely addition to any (peaceful) tank. They boast some beautiful stripes and spots, as well as long, whisker-like appendages that are called ‘barbels.’ The Corydora uses its barbells to help dig through sediment and guide organic, edible matter to its mouth: a true bottom feeder. 

Because of this, they like to eat their food on the ground and prefer special ‘sinking pellets’ (rather than floating food like flakes). 

The substrate in a tank with Corydoras should be composed of a fine sand, rather than pebbles or gravel, or they will abrade their sensitive skin as they feed (and even potentially lose their barbells).

2. The Common Clownfish

The Common Clownfish is one fish you’ve almost certainly seen before. These brightly colored characters are anemone-dwellers, and peaceful among their own species. They will not tolerate other species of Clownfish, however. This will cause aggressive behavior.

Common Clownfish are weak swimmers and will struggle to swim in a strong current. Aquatic plants, most notably anemone, give them somewhere to rest and also gather up detritus that Clownfish will eat. 

Just keep in mind that anemones safe only for a rare few fish, such as Clownfish and Anemone Fish. Anemones evolved specially to kill most fish and other aquatic creatures. A nice, lush plant like Java Moss will also work OK!

3. The Goldfish

You are probably the most familiar with the Common Goldfish. This is a simple, brightly colored orange fella. There are also lots of other kinds of Goldfish to pick from, some with appearances that are much showier.

For example, you have the Bubble Eye, the Comet, the Celestial Eye, the Fantail, the Lionhead, the Ryukin, and the Black Moor. As its name implies, the Bubble Eye has big ‘bubbles’ (fluid-filled sacs) under their eyes, which give them a very unique look!

The Celestial Eye, on the other hand, has enormous, golden eyes that shimmer. True to its name, the Lionhead Goldfish has a huge, magnificent head. If you’re looking for a twist on the more classic Goldfish appearance, there’s the Black Moor.

All species of Goldfish are known for their beautiful appearance and friendly behavior. Just make sure not to pair big Goldfish with particularly small fish, or the Goldfish may see them as a snack!

4. The Neon Tetra 

Neon Tetras are tiny, brightly colored fish that are peaceful and easy to care for. They live in pretty little shoals and prefer plenty of vegetation to mimic their native environment – the lush streams and small rivers of South America. Java Moss is a favorite, as is Coontail.

In a Neon Tetra tank, you will need at least 10 gallons, to accommodate a small school, and 15-20 gallons for schools that are larger. 

Also, make sure that your Neon Tetra tank mates are similarly peaceful; they are so small that meat-eating omnivores often consider them a snack!

5. The Threadfin Rainbowfish

The Threadfin Rainbowfish is a truly beautiful fish with a super-shimmery body and long, flowy fins that look like wind-blown silk. These fins are very delicate, matching the fish’s exceptionally timid personality. 

Because Threadfin Rainbowfish are so sensitive, they require similarly peaceful companions. In fact, aggressive, nipping tank-mates can seriously damage the Threadfin Rainbow Fish’s fins.

Not only is this distressing and painful, but it makes room for serious infections. 

When it comes to care, you’ll need to pay close attention to the Threadfin Rainbow Fish’s diet and water conditions. 

These fish do not like to compete for food, so during feeding time, you’ll need to watch and ensure that they get enough to eat (according to the serving instructions on the food container).

Threadfin Rainbowfish will also be killed off swiftly by any fluctuations in temperature or pH.

6. The Dwarf Gourami

The Dwarf Gourami is super-unique, in that it must have access to the surface of water. They breathe straight from the air.

These peaceful, rather shy fish get along best with other small and easy-going fish like Neon Tetras and Platies. They are also too small to prove a threat to snails, so they can also neighbor with these in a tank.

Dwarf Gourami scales have an almost neon, jewel-like shimmer. The males are typically orange with turquoise stripes, while the females tend to be a more modest blue-silver. 

7. The Guppy

Guppies are tiny, good-natured fish that get along well with similarly peaceful fish, like Cory’s, Neon Tetras, Platies, etc. They are plump fish that often boast bright colors, earning them the nickname ‘Rainbow Fish.’

Guppies can be a bit shy and prefer plenty of vegetation in the tank. Their favorite plants are Hornwort or African Sword-Tail.

Table of Fishkeeping Difficulty for Popular Fish

GouramiRainbow ThreadfinsAngel Fish
GoldfishPlecosMoorish Idols
Neon TetrasCichlidsDiscus
GuppiesPlatiesTiger Barbs
Cory CatfishDwarf Pea PuffersCharacins
small tiger barb fish

How do You Pair the Fish in Your Tank?

Some of the Most Peaceful Fish Are: 

  • Corydoras (Cory Catfish). Despite their hard-shelled appearance, the Cory Catfish is an easygoing bottom feeder. 
  • Threadfin Rainbow Fish. Threadfin Rainbow Fish are not just peaceful, they are downright timid. Do not pair them with fish that are known fin-nippers, or their delicate, flowy fins will suffer. 
  • Platies. These are fine, fat little fish, featuring bright colors and speckle patterns. Platies must be paired with similarly small and friendly fish, like Corydoras or Gourami’s.
  • Guppies. Guppies are remarkably peaceful and charmingly colorful. They are fantastic community fish (so long as there are no aggressive fish to bully or prey on them).
  • Swordtails. Peaceful Swordtails look much like the common goldfish; except for their long, distinctive tails, which give them a rather striking look. They are usually orange, with scales that shimmer.

Some of the Most Aggressive Fish Are:

  • Cichlids. Many Cichlids are extremely aggressive and will not only kill fish but also each other. Some are a bit less aggressive but should still be paired only with their own kind and other tough fish (so, probably not any of the peaceful fish listed above).
  • Characins. Despite its innocuous appearance, the Characin is a known killer. They don’t just nip other fish, they eat them. So, you will definitely want to think about what fish you pair with these or choose another fish altogether. 
  • Tiger Barbs. While the Tiger Barb is not exactly vicious, it is a mischievous fin-nipper. Among its own kind, this is normal competitive or even playful behavior. Fish with sensitive fins and gentle temperaments, on the other hand, will suffer. 
  • Angel Fish. While Angel Fish compete among each other at times, they are not generally aggressive. That being said, the gorgeous Angel Fish is an opportunistic eater, and will likely consider small fish a quick and easy snack.
  • Dwarf Pea Puffer. Dwarf Pea Puffer males should virtually never be kept together. This cute, round-bellied fish is another renowned fin-nipper. 

What Diseases Can Fish Get?

Sadly, there are some fish diseases that can prove deadly. They are most often treated with antibiotics and special disinfectants and can be prevented by maintaining the proper water temperature and pH, and, just as importantly, clean water. 

Common illnesses and diseases include anchor worm, dropsy, fin rot, and a variety of mold and fungal infections.

If you notice any signs of illness in your fish, act quickly, as their condition is sure to worsen. Fast treatment can be a lifesaver. 

How Do You Breed Fish?

The key to inducing fish to breed is to gradually increase the water temperature and lighting in the tank. This simulates springtime, which stimulates fish to mate in the wild.

If you are planning to breed fish, you will want to ensure that their fry will not get eaten by other fish. The best bet is to have your fish spawn in another conditioned and comfortable tank. 

Leave the fry in there until they’ve grown enough to survive on their own. Otherwise, even their own parents may mistake them for little shrimp to snack on or some other kind of edible, organic matter. 

Don’t breed your fish until you’re sure you know what you’re doing, because it can be pretty complicated compared to breeding other animals. The proper settings must be provided so that all goes peacefully, and to ensure the fry’s survival.

feeding a koi fish

How Does Fish Keeping in a Pond Compare?

Compared to a tank, you will need to pay extra attention to the temperature in a fishpond. This goes doubly so in the winter. 

They will also need a much larger filter than they would in a tank. Unlike in a tank, wild predators like birds, mongooses, and bullfrogs, can also be a risk. 

Some of the best and hardiest fish to keep in a pond are Mosquito Fish, or the classic Goldfish or Koi.

Final Thoughts

So, what do you think? Are you interested in becoming a fish keeper? It’s a great hobby, and it’s also a cool way to spruce up your home with some living decor. 

All that you need to get started is a bit of know-how, some supplies, your fish of choice, and of course, the right size of tank!

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