It’s an exciting day, everything is plumbed in, your lights have their timers working, you have you saltwater mixed and up to temperature, your tank is cycled and water parameters are stable… it’s time to start stocking!

Royal Dottyback
Royal Dottyback – very aggressive

Hopefully, when you started your tank you had a bit of an end-goal in sight, and you have built your tank to suit that end goal, for example you know that at some point you would like to keep Tangs, so you have gone out and bought a nice big tank for them to swim about it. Or, maybe you’ve always wanted a predator tank with your prized fish being a Lion Fish. Whatever your end goal is, your tank should be set up to accommodate that.

So how do you choose your first fish? With lots and lots of research. I’m going to break this down into easy to follow steps. This has been written with the assumption you have cycled your tank fully, and you are not planning to use bottled bacteria.

  1. Realise your end goal. Be it a predator tank, mixed reef, fish only, coral only, SPS, Softie, LPS dominated, whatever it is write that down.
  2. Write a list of the fish you would like to keep. Initially pick fish that attract you for their colour, shape, movement or the job they will perform in your aquarium.
  3. Research every fish on that list. When I say research, I mean their preferred environment, feeding requirements, temperament, tank sizing requirements, how big they will get, what job (if any) they will perform in your aquarium, are they prone to certain diseases or parasites, literally everything you can think of, write that down against your wish list. I will put the list I use at the bottom of this article.
  4. Compare your wish list to your end goal. Go back through that list and start crossing out any of the fish that don’t match your end goal, will get too big for your tank, won’t like the substrate you are using, won’t have a sustainable food source in your tank, anything that is not compatible with your end goal and current set up, cross them out!
  5. Narrow down your list further. So you now have a wish list of fish you can keep & would like to keep. For your first fish, you want something on that list that is nice and easy to keep. This means something hardy, not prone to disease, not a crazily expensive fish and not territorial. From your list pick two or three fish that would make a good first fish.
  6. Head to the store! Go to your local fish store armed with your list of two or three fish and buy them. If your tank is small, maybe just buy one until your bacteria has adjusted to suit the bioload change, if it is larger you will be able to get a few fish. Don’t go and buy all the fish on your list at once, adding all the fish in one go will cause an ammonia spike. Do not deviate from your list because a pretty fish caught your eye!

Things to research before you buy any fish

Below you will find a list of questions I research before buying any fish. My end goal is a mixed reef tank.

Tang with Ich
Tang with Ich
  • Reef Safe: Yes / No / With Caution
  • Adult Size:
  • Minimum Tank Volume:
  • Prone to disease:
  • Considered Hardy: Yes / No
  • Recommended order to add into the tank: First / Whenever / Last
  • Temperament: Peaceful / Aggressive / Semi-Aggressive
  • Feeding Requirements: Herbivore / Carnivore / Omnivore / Specialist
  • Invertibrate/clean up crew safe: Yes / No
  • Average Cost:
  • Preferred substrate: Any / Fine Sand / Bare Bottom / Large Sand
  • Open Water Swimmer: Yes / No
  • Hiding Spots Required: Lots / Few / None
  • Preferred Water Parameters: (temperature, pH, Alk, etc)
  • Job within the aquarium:
  • Flow Requirements: Low / Medium / Fast
  • Number of species recommended per tank:
Royal Gramma
Royal Gramma – Perfect first mixed reef fish

With the above list, you should be able to determine if the fish you are looking at is compatible with your tank and your end goal. It may seem like a lot to look at, but at the end of it you will have a list of compatible fish and you will know at what point you should consider adding them to your tank.

This hobby is a reward and engaging one, but if you don’t put the time into making informed decisions you will eventually be burned with it which could result in loss of stock, illness within your aquarium or even frustration to the point of giving up! Putting a bit of time into making your decisions will pay off in the long term.