17. Aquarium Fish Selection

Myths About Selecting Fish for the Aquarium

Selecting fish has become very controversial with the advent of social media and the many people who parrot a myth over and over again. These purveyors of myths about fish selection are known with some disdain as the “fish police”. Some of the myths about fish selection include:

  • Tropical fish don’t thrive in water conditions outside their native water conditions.
  • Never mix American and African Cichlids as they will have huge aggression issues.
  • Mixing fish species from different continents or different biotopes will shorten the life of the fish.
  • Carnivores and herbivores require different diets in an aquarium
  • Tropical fish thrive in water conditions outside what occurs in their native waters because they have been bred in captivity.
  • Neons are an easy fish which are good for a new tank.
  • Plecos require wood in their diet.
  • Goldfish don’t thrive in warm water aquariums.
  • Common, comet, fantail, sarasa and shubunkin goldfish are not fish for beginners.
  • Goldfish need at least twenty to thirty to forty to fifty gallons per fish.

None of these myths is true

Glofish Aquarium
Glofish Aquarium

Beginner Fish for Aquariums under Fifteen Gallons

As for the selection of fish for a beginner with a small tank there are some fish which are quite accepting of the mistakes we all make as beginners to the hobby. These fish are:

  • All varieties of glofish except the shark* 
  • Platy
  • Endler Livebearer
  • Red Eye*, Black Phantom*, Black Neon* and Black Tetras*
  • Harlequin Rasbora*
  • White Cloud Mountain Minnow
  • Betta (alone in the tank)
  • Corydoras*
  • All types of small barbs*
  • Various small Danios*

*schooling fish

All these fish will do well in any water from 6.5 to 8.5 pH and 65 to 85 degrees Fahrenheit (18 to 29 degrees Celsius). They will all co-exist with each other except for the betta. In a small tank bettas sometimes kill all tankmates and sometimes they are peaceful.

Note that schooling fish MUST be in schools of at least six fish. This is NOT OPTIONAL.

Tropical Fish Aquarium
Beginner Tropical Fish Aquarium

Note I do not put mollies or guppies in the easy beginner fish list. I find guppy and molly strains now a days to be very inbred and weak and I do not keep them anymore. Note that neons, cardinals and rummy noses are NOT easy fish as they come from something called a “black water”. Also note that 75% of the various dwarf gouramis have a virus which kills them at 8 to 12 months of age, so avoid dwarf gouramis.

Note that many put goldfish in very small aquariums and are very successful with them. Common, shubunkin and comet goldfish are very easy fish and do very well in small aquariums. They have been bred for a thousand years in China in small containers and have undergone “inadvertent selective breeding” to become fish that are quite capable of thriving in very small tanks. Just don’t reveal on social media that you are doing that. The PETA folks will jump all over you for “cruelty to animals”.

Goldfish Aquarium
Goldfish Aquarium

Beginner Fish Selection for over Fifteen Gallons

As for the selection of fish for a beginner with a tank over 15 gallons there are some fish which are quite accepting of the mistakes we all make as beginners to the hobby. These fish are:

  • The List Above
    • All varieties of glofish except the shark* 
    • Platy
    • Endler Livebearer
    • Red Eye*, Black Phantom*, Black Neon* and Black Tetras*
    • Harlequin Rasbora*
    • White Cloud Mountain Minnow
    • Betta (alone in the tank)
    • Corydoras*
    • All types of small barbs*
    • Various small Danios*
  • Shark Glofish
  • Larger Barbs*
  • Larger Danios*
  • Swordtail
  • Gouramis (other than the dwarf gouramis)
  • Siamese algae eater (not the Chinese algae eater)
  • Bristlenose Pleco
  • Common and comet goldfish

*Schooling Fish

All these fish will do well in any water from 6.5 to 8.5 pH and 65 to 85 degrees Fahrenheit (18 to 29 degrees Celsius). They will all co-exist with each other save for the fact that goldfish will eat guppies and other small fish. Also the glofish sharks tend to be aggressive and get large.

Platies and Mollies in an Aquarium
Platies and Mollies in an Aquarium

Fish Which aren’t Recommended

And then there are fish decidedly not recommended for beginners. Topping the list:

Do not get Neons for a new Aquarium!

Neons are a “blackwater” fish which needs very bacteria-free, crystal-clear water that one only gets in a tank over four months old which is over-filtered. Similar blackwater fish not recommended for beginners include:

  • Neon Tetras
  • Ram Cichlids
  • Oscars
  • Discus
  • Rummy Nose Tetras
  • Hatchetfish
  • Clown loaches
  • Glass catfish
  • Neocardina shrimp

More about this on this link to blackwater fish:

17.3. Blackwater Fish (links to aquariumscience.org)

Also note that 75% of the various dwarf gouramis have a virus which kills them at 8 to 12 months of age, so avoid dwarf gouramis..

Blackwater Aquarium
Blackwater Aquarium

Note the guppy and molly are not on the “beginner” list. The highly inbred fancy guppies are very difficult fish for some. Especially the males seem to be very short lived.  But many beginners are successful with them. Different guppy strains are inbred to different degrees and thus the huge variation in viability. Mollies are genetically prone to a disease called the “shimmies” due to inbreeding. More about guppies and mollies in this link:

17.6 Guppies and Other Livebearers (links to aquariumscience.org)

Schooling Fish

Schooling fish are very common in the aquarium trade. They tend to be very brightly colored. But they MUST be in schools of at least six in order to insure tranquility in one’s aquarium.

A Schooling Fish Marosatherina ladigesi Celebes Rainbowfish
A Schooling Fish, Marosatherina ladigesi, Celebes Rainbowfish

Schooling fish MUST be in schools of at least six and preferably ten fish. This is not to keep them “happy”. This requirement is because, in an aquarium with other fish species, these fish CAN become very aggressive if not in a school. Groups of two or three fish of species like tiger barbs, serpae tetras, black phantom tetras, zebra danios and most glofish (bettas and sharks being the exceptions) have become killers in SOME aquariums. Sometimes these fish have killed much larger fish like angelfish if they are not in a decent sized school. So a school is a requirement.

The reason behind this schooling requirement is that schooling fish become very afraid when they can’t find a school. They become very defensive and lash out at other fish which get too close. So it is not aggression, it is fear which creates the problem.

Goldfish aquarium
Goldfish aquarium

Goldfish

Probably the most common fish that beginners start with is the goldfish. This fish is the target of a concerted PETA (People for the Ethical treatment of Animals) campaign to “humanize” fish keeping in line with their extremist views. Contrary to what all the many folks from PETA say on social media everyday, it is possible to raise a thriving healthy goldfish to a very old age in a small aquarium. If you want the truth about keeping goldfish go to this link:

17.5. Goldfish (links to aquariumscience.org)

Betta Aquarium
Betta Aquarium

Betta

Another fish which has had a lot of propaganda spewed about the size of its tank is the betta. For information on keeping this somewhat unique fish go to this link:

17.7. Aquarium Bettas (links to aquariumscience.org)

Malawi Cichlid aquarium
Malawi Cichlid aquarium

Lake Malawi Cichlids

And a very popular type of tank that many beginners like to do is an African Cichlid aquarium with Lake Malawi Cichlids. This is a link to information on them:

17.4 Lake Malawi Cichlids (links to aquariumscience.org)

And it generally is quite challenging to mix plants with any African or Central American cichlid. The cichlids just love uprooting the plants. As the following tank can attest to:

Beginner Tank Mixed Cichlids
Beginner Tank Mixed Cichlids

Nano Aquariums

Another special situation is the stocking of very small to small tanks. This is called a “nano” aquarium and is covered in this link:

17.9. Nano Aquariums (links to aquariumscience.org)

nano aquarium
nano aquarium

Cold Water Aquarium

Some folks want an aquarium which can go down to 50 to 60 degrees F. In addition to goldfish the following fish do well in colder water: danios, white cloud mountain minnow, Hillstream loaches, weather loaches, Neocaridina shrimp, guppies, platy’s, Buenos Aires tetra, bloodfin tetra, cory’s, plecos  and 2 spot, gold, green and rosy barbs.

Breeding Fish

Breeding fish, eggs and fry do “best” with the following:

  • Bacteria free, crystal clear, over filtered water
  • A food with at least 40% protein and 10% fat in it
  • Calcium both in the water as a GH over 4 and in the food as fish meal (includes bones)
  • Temperature, pH and TDS (total dissolved solids) in the range of their native waters
  • Great aeration with either “choppy waves” at the water surface or a big air pump and air stone.

These are for “optimum” breeding. There are many fish (livebearers, African and Central American cichlids) which breed like rabbits in ANY water and any food. Try giving away juvenile convicts some day.

Add plaster of Paris or Tums (calcium carbonate) to increase GH. Read the label of the food you feed to see the protein and fat levels. And hunt for either “fish meal” or “whole fish” as one or preferably two of the first three ingredients in the food.

Lake Malawi Aquarium
Lake Malawi Aquarium

Selecting Fish

These are links to three different ways sometimes used to select fish. Some prefer to do their aquariums this way and that is fine. “Different strokes for different folks”:

17.1. Selection via Native Water Chemistry (links to aquariumscience.org)

17.2. Biotopes (links to aquariumscience.org)

17.2.1. Blackwater Biotopes (links to aquariumscience.org)

And these are links to keeping specific fish:

17.3. Blackwater Fish (links to aquariumscience.org)

17.4. Lake Malawi Fish (links to aquariumscience.org)

17.5. Goldfish (links to aquariumscience.org)

17.5.1. Types of Goldfish (links to aquariumscience.org)

17.5.2. Size of Goldfish (links to aquariumscience.org)

17.5.3. Stocking Goldfish (links to aquariumscience.org)

17.5.4. Goldfish Care (links to aquariumscience.org)

17.6. Guppies and Livebearers (links to aquariumscience.org)

17.7. Bettas (links to aquariumscience.org)

17.8. Oscar (links to aquariumscience.org)

17.9. Nano Aquariums (links to aquariumscience.org)

17.10. Aquarium Shrimp (links to aquariumscience.org)

17.11. Discus (links to aquariumscience.org)

17.11.1. Discus Husbandry (links to aquariumscience.org)

17.11.2. Filtration for Discus (links to aquariumscience.org)

17.11.3. Water for Discus (links to aquariumscience.org)

17.11.4. Food for Discus (links to aquariumscience.org)

17.11.5. Discus Pheromones (links to aquariumscience.org)

17.11.6. Breeding Discus (links to aquariumscience.org)

17.11.7. Discus Aquarium Photos (links to aquariumscience.org)

17.12. Axolotl (links to aquariumscience.org)

Rainbowfish Aquarium
Rainbowfish Aquarium

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Translated in dutch by : Joost Abrahams
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