Who knew adding fish to a fish tank could be so complicated? Does it really need to be so complex? What fish can you have? What fish should you definitely not have? What order should you be adding the fish to your reef tank? Let's try and answer all those questions and cover the topic of fish in the reef tank.
First thing is first, if you're setting up a new reef tank then make sure you're at the right stage to be able to add livestock. You need to make sure your tank has cycled and is stable. Saltwater fish are more demanding and generally less hardy than freshwater fish so if you're brand new to the salt side of life then make sure you've researched and understand the general care requirements for keeping a salt water aquarium and marine life. This is really important not only at the beginning of keeping a reef tank but at all times. As reef keepers, fish keepers, crab keepers, coral keepers, or whatever; we have the responsibility to look after it. Ultimately, these are animals that rely on us to keep them alive and give them the best living conditions possible. So, in that spirit, here are a few bullet point guidelines that should help you to determine what fish you can keep in your reef tank;
Skill level
Are you a beginner or an expert? If you're just getting into keeping saltwater fish then by default you will be a beginner. In fact, a fair few reef keepers who have been in the hobby for a couple of years now would still consider themselves as beginners. Hardly any consider themselves as experts which I would say is a status probably reserved for those reef keepers who have been in the hobby decades or who work in the industry and hold a degree or equivalent in marine biology for example. The reason why you should determine what skill level you are at though is that some fish are hardier than others. Some have very specific care requirements, specific diets or even need species specific setups just to accommodate them. As an example I would say Ocellaris Clownfish are a typical beginner fish because they are hardy and don't need any specific setup whereas Copperband Butterfly fish should probably be cared for by experienced reefers. They are a bit more delicate and can be picky when it comes to food. The Blue Spot Ray on the other hand is expert only. It needs a very specific setup and care requirements to keep long term happily so shouldn't be kept by beginners. Now whilst its probably quite tempting to want to rise to the challenge of keeping a more delicate fish, there are plenty of fish out there that are deemed suitable for beginners so don't assume just because it's a 'beginner fish' that it will be boring or not worth keeping.
Maximum fish size
'That little blue fish that looks really nice in the shop would be right at home in my nano tank at home'.
'It's only small so it would have loads of swimming space and there's not much else in the tank so it would have no problem settling in'.
That little blue fish you're looking at is a Regal Tang and yes you're absolutely right, it is small and does look really nice in the shop but in 12 months time I guarantee it will be twice the size. It will keep on growing until it reaches about 1 foot / 30cm! So no, it won't be right at home in your nano tank at home I'm afraid. This is something I see all too often on social media. Someone will post an image of a fish along with the caption 'just got this, can anyone tell me what it is?'. Firstly, no shop should be selling you livestock that you don't know how to care for and they should be checking with you to find out what system you have to make sure you have what is needed to keep it. Secondly, the responsibility is also with the fish keeper. Research research research and never ever impulse buy! Back to maximum fish size; when you are looking at what fish to add always plan off the size it will be when fully grown not the size it is now. Fish size is also the better metric when deciding what you can keep as opposed to the more widely used minimum fish tank size because you need to factor in the swimming space it needs. The best way to explain this is with an example; a Blonde Lipstick Naso Tang needs a minimum tank size of 700l. What if your tank size is 2ftx2ft but you have a huge sump that takes your total water volume to over 1000l. Is this suitable for a Blonde Naso? No, because it has no swimming space. The fish reaches 45cm, in a 2ft tank it will only have 15cm of swimming space in any one direction. What if you have an 8ftx1ft tank? Plenty of swimming space in one direction but no room to turn around. Is that any good? What about if you have a 8ftx3ft dream tank but its rammed full of rock scape and coral wall to wall, sand bed to water surface? Plenty of swimming space on paper but in reality there's not much room. So really, it's a judgement call by you to decide whether or not your reef tank is suitable for the fish you want. Just make sure you make an informed judgement call by researching the fish you want and if you don't think you can keep it then don't. As they say, there's plenty more fish in the fish shop!
Maximum number of fish
The general rule of thumb for how many fish you can keep in a reef tank is 1 inch of fish per 5 gallons of water. I personally don't like this rule because it's vague and it doesn't address the main factor that determines how many fish you can have and that is tank filtration. An example here is; you have a 300l reef tank so in theory you can keep a fair few fish but what if your filtration setup can only really handle half the number of fish you think it can. If you added all the fish according to the 1 inch per 5 gallon rule then you'd be unable to maintain your system because nitrate and phosphate would be uncontrolled. On the other hand, if your filtration is really good and you can handle more than the maximum number of fish according to the 1 inch per 5 gallon rule then should you add more? You could pack your reef tank full of fish but you have to consider quality of life for your livestock. No one wants to live in an overcrowded space. Plus, consider swimming space and the size the fish will be when they reach their max size.
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Fish compatibility
Unfortunately not all fish get along together, some are just down right jerks whilst others are too easy going for their own good and end up getting bullied by more boisterous tank mates. Some fish are fine with others except those that are a similar shape and colour. These fish tend to be the territorial type which stems from the need to protect their food source in the wild. If there's only so much food available then fish are going to start being very protective over it in order to secure their own survival, such is nature. To further complicate the process of adding fish, it is generally a good idea to add fish from the most peaceful to most aggressive in order to prevent the more boisterous fish from establishing large territories thus preventing the shy fish from settling in. So, like I said in the previous point, the golden rule is research research research and never impulse buy. To help you out there's a useful compatibility guide here which lists the majority of fish available and tells you if they're compatible with others. Have a look at the fish' temperament on species information as well to give you an idea of whether it'll be peaceful and reef safe or a more aggressive predator. This will also tell you if the fish will be compatible with inverts and corals which is also going to be a big factor when you decide what you want in your aquarium.
So where to begin?
1) Write a fish list. This is a wish list of the fish you'd like to add to your aquarium. Have a look online and around the shop. Take a note of what you like and then you can begin the research process.
2) Figure out if the fish on the list are suitable for the size of your aquarium.
3) Consider the quantity of fish you can keep in your aquarium factoring their potential max size too.
4) Use the fish compatibility chart to make sure your fish will be able to co exist in your aquarium (including whether they are reef safe, invert safe or okay to be in a fish only system if that's the route you're going).
5) You should now have a whittled down list of fish that you want and are suitable for your setup. Write the finalists down in order from most aggressive to least aggressive. You will add the most aggressive fish last. This part of the process can be tricky and often relies on experience so if in doubt, ask! Pop into the shop and have a chat or even better, get us involved in the process when you're having a look around the shop. We're happy to have a chat through what options are out there and what to steer clear of.
6) You're all set now to add your livestock. Slow and steady wins the race though!
That covers some of the basics on what to consider when looking for fish. The golden rule though is always research research research and never impulse buy! If in doubt, come in store, have a chat and look around!