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Marine fish keeping guide for beginners

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Marine fish keeping, the complete beginners guide.
by Bill19 Published on 14-08-2009 21:48

I decided to write this as there is not much basic info on everything in marines out there apart from books, and lets face it they cost money! The article covers equipment, setting up, maintenance, and live stock. If you spot any thing which i have missed feel free to pm me, and i apologize for any spelling mistakes! Enjoy


Image credit- Race Fox

Marine fish and coral with their vibrancy, interesting behaviour, and pure beauty are amazing things to have in your home. Firstly I would like to expel the myth that you should keep freshwater fish before keeping marine fish, they are higher maintenance and more expensive, but they aren’t always (apart from the latter!)! The reason most people fail, or find it hard is that they treat it as a freshwater aquarium! Which is not the right way to go about it, they are so different you may as well forget almost everything you know about fresh water, any way...
Welcome to the salty side!

Is it right for me?

Marine fish keeping isn’t a doddle, and it certainly isn’t cheap, things can go right but then something can knock you right back. You have got to be dedicated, you have to be able to afford the necessary equipment (but you can get equipment bit by bit, there nothing wrong with taking things slow), and most of all you have to care! Here are some factors to consider when choosing to go marine:
• There is quite a bit of equipment you have to use, can you afford the electricity bill?
• Most marine fish are wild, are you willing to keep wild fish?
• It is quite a lot of work, do you have the time?
• You will need to use RO water for a reef, making RO is very wasteful, along with using, sometimes, lots of electricity, are you fine with making the ecological impact?
You ready?

The Equipment

You can’t keep them if you don’t have anything to keep it in! First I will talk about all the different components in a marine aquarium, and then about the aquarium itself.

The heart of any aquarium

The filter is the most important thing in your aquarium! No wonder there’s so many ways of doing it! Berlin, ecosystem, etc. I won’t be explaining all of these things just what make the basis of a good simple filtration system. All filter medium need flow through them for it to do any good! The tanks water needs to be circulated through the media at least 10 x the tanks total volume per hour (e.g. 100 litre tanks will need 1000lph pump). The filter media (apart from all of the live rock) can be put in an external canister filter, a sump, a trickle filter, or any other conventional filter.
“What’s a sump?” I here you ask, a sump is a tank underneath the display tank in a cabinet, it contains most of the filtration equipment and media. The sump has many chambers for the things to go in. The most common way of getting the water in to the sump is to have a weir or over flow (you can buy tanks with these already done, it’s not wise to try it yourself unless you know what your doing!), it is basically a hole in the bottom of the tank, but it is behind a barrier, so the water has to over flow over that barrier. Then it goes in to the sump, flows through the chambers and media, and the last chamber contains a return pump and it is taken back up and poured back in to the aquarium. Sumps are fantastic as they give you lots of extra volume, and you can hide all the ugly equipment in there out of site! You don’t have to have one, but they are recommended!
Filtration is broken down in to three main types:
• Biological- This is probably the most important yet the most complicated scientifically of the types of filtration. Basically, fish waste, dying animals and plants, and rotting food, (decomposition of organic products) produce ammonia (NH3+), a very toxic thing which you need to be 0ppm at all times, special bacteria called nitrifying bacteria change this ammonia in to a less toxic nitrogen compound called nitrite (NO2-).
Nitrite should also always be 0ppm, it is not as lethal as ammonia, but still dangerous especially to invertebrates!
Nitrite is then broke down further by the good nitrifying bacteria in an even less toxic compound called nitrate (NO3-). In a reef aquarium this needs to be as low as possible, preferably 10ppm or less, and if you wanted to try some of the more difficult corals, then it would need to be almost zero. For a fish only aquarium 20ppm is a goal, but it’s OK for it to be a bit higher. But if it gets to 50 or above you need to be looking at your system and seeing where the problem is coming from, although the fish will be able to tolerate it, it’s still not the best for them, and a level of over 80 should definitely be avoided! High nitrate can also cause problem algae to flourish. But, nitrate cannot be broken down further by the nitrifying bacteria, you have to dilute with water changes and plants and algae will take in the nitrates.
Here’s a diagram from the internet which will help explain it:


For Biological filtration to happen, you have to have the nitrifying bacteria, they need a substrate to live within. Bio balls and ceramic media can be used for this along with other commercial items, but they aren’t the best, what you should use and what all great marine systems are based on is, live rock. Live rock is not rock which can walk and talk, it is very porous rock which is from reefs (although some nowadays is ‘eco rock’ which is cement based and is exactly the same and porous and is put in the sea for a while so it becomes live, and so we aren’t relying on ‘wild’ reef live rock). Inside the live rocks thousands of holes live the nitrifying bacteria, along with lots of micro fauna like copepods, crabs, shrimps, bristle worms etc. You need at least 1kg of live rock per 10 litres to sufficiently filter the aquarium. Also you can get live sand where bacteria and micro fauna can also live, however there is little point in buying live sand, as it will be seeded by the live rock. Live rock is also used to decorate a tank so most of it is not kept in a filter.
I also mentioned earlier that nitrate can be absorbed by plants and algae; this is where a refugium comes in. A refugium is a no fish zone, and it contains macro algae (caulerpa and cheato are the most common algae used, but cheato is the preferred algae), it can also contain, live rock, or a deep sand bed. Plants can sometimes be used such as sea grass (hard to get hold of) or even small mangrove trees! The refugium needs to be lit, a small compact light (such as an arc pod light or solaris light) are commonly used, but submersible LED’s can also be used. Many people light refugiums 24/7, however this can lead to the plant being unhealthy, and any micro fauna living in it to die, it would be like us with the sun out all the time! I would recommend a lighting period for a refugium to be on for around 18 hours, and of for 6 hours. A refugium can be put in the sump, can be hung on the tank, or you can modify a standard filter to have one! All you need is light and the algae! A refugium does basically the same job as a protein skimmer (I will come on to these later), if you don’t get a protein skimmer I would recommend a refugium. But refugiums don’t just remove unwanted compounds, The algae also provides a home and food for micro fauna such as copepods and other things which is a valuable natural food source for many fish.
• The next type of filtration is mechanical. This is an awful lot more simple! It is the removal of small and large particles. It is simply done by filter wool/floss or sponge. The filter wool/floss or sponge needs to be washed (under tap then rinsed in RO) or changed every week, as you do not want this becoming biological, as it unlike live rock, will become a nitrate factory and cause bad water quality. I prefer filter wool as it is cheap so can easily be changed weekly
• The last type is chemical; it is the absorption of molecular compounds in the water by a filter medium. The most common of these is the tiny bubbles of a protein skimmer. A protein skimmer is a cylinder contraption which can be hung on, or sat in the aquarium (depending on model), it releases tiny bubbles (either via a wood diffuser with an air pump or air injection), the protein skimmer is the best thing to do this, my motto is, if you can afford and fit one, get one! And also try and over skim, go for a skimmer which the manufacturers rate is suitable for a tank which is double your tank size. If you can’t fit or afford one, then don’t, chemical filtration can be done by other mediums, such as carbon, and seachems purigen, I prefer purigen, as it removes only the bad compounds not the good, carbon removes both, there are also many other products out there for you to find, but it all starts to get a little bit too much like a science lesson!

Those are the three main bits of filtration, however there is one more compound which you need to keep to minimal levels, it is called phosphate (PO4), like nitrogen compounds it is from organic waste products. It needs to be kept as close to 0ppm as possible, as it will stress out and kill invertebrates. To keep phosphate down there are many phosphate removers on the market which remove it sufficiently, plants and algae also take in phosphate like they do nitrate, so a refugium can help too!

RO water

RO (reverse-osmosis) water will need to be used in modern day marine aquarium. This is basically water which has been put through a special filter to remove pretty much everything! You can either buy yours, or make your own! If you’re going to have a relatively large aquarium of say 300 litres you are probably better off with your own RO unit, but if your aquarium is smaller than that, because of the small amount you will use, you just won’t make your money back on the unit, and would be better off buying your water from you local fish shop (LFS).

Light and heat

The next components are also very important, but very simple:
• Heat- Tropical marine fish and invertebrates need a constant temperature of 24-26c (75-79F). All you need to do this is a glass aquarium heater, put it horizontal at the bottom of a tank preferably in a high flow are (e.g. next to a filter intake, under a pump or power head). You can get different wattages for different size tanks, the manufacturers will state which size is right for what size tank.
• Lighting- The lighting you usually get with tanks now a days are T5 tubes, or compact (PL) bulbs. T5s are most commonly used, but T8 will suffice for a fish only aquarium or very low light corals, but I will come on to how much light in the coral chapter. You need to have half marine white and half actinic (blue), this is perfect for corals and shows off the fish colours better, and it looks a lot more ocean like. The king of lighting is metal halides, these are very bright, and most large reefs use them, they come in wattages from 70w to 1000w! They also direct light in beams like the sun, so you get a ‘shimmer’ effect like you do in the ocean. The drawback of metal halides however, is that they are expensive to run, and they get very hot and can make the tank over heat! (I will address the problem next). There is another way to get the ‘shimmer’ effect, without the electricity bills and heat! LED’s. At the moment the only LED’s readily available are TMC aquarays. But more will come on to the market soon and will be competitively priced! You can light a tank solely with LED’s, however at their present state they are usually just used to supplement T5’s. Mainly because you will need a lot of them to match halides! However you only have to replace them every ten years or so, and they are the future!
• Cooling- yep, aquarium equipment gives off heat, especially lights such as metal halides! Most tanks in the UK fitted with fluorescent lighting don’t have a problem with overheating, however if you live in a hot country or you are using metal halides, you may need to cool your tank! The most efficient way to cool a tank is to use a chiller, however these are expensive to run and buy, but well worth the money if you have serious heating problems. Most people however just use fans, to cool the metal halides. It’s wise to keep a few RO ice cubes in the freezer incase of any overheating emergency.


As I said earlier a marine tanks volume needs to be circulated at least 10x an hour for it to be sufficiently biologically filtered. The filter pump will usually deliver this. However if you want to keep corals then you need it be circulated around 20x an hour or more (depends on the coral species). This extra flow is provided by power heads, these are basically just pumps which are kept inside your aquarium! The best power heads are ones which have a wide `out flow’ point, so the flow isn’t one jet, and more of a flow. It is better to have more smaller power heads then large one, as this will make more natural flow and will disturb (to get rid of debris) more areas Also on the market today there is wave makers, these are fantastic and really make natural flow! It rocks the water back and forth like waves do, and unlike power heads, you only need one or two!

UV sterilisers

Ultra violet is an electromagnetic wave which has a high frequency; it is given off by special bulbs. UV kills tiny things in the water, so it’s great to help to keep disease and algae blooms and bay. A UV steriliser is a structure with a UV bulb inside, water is slowly pumped through it, and as it passes the UV bulb it is sterilised. These are great to have with fish which are sensitive to disease like white spot such as puffer fish and powder blue tangs. But otherwise they are not needed, but if you can afford and fit one, why not get one?

The little things

Test kits, salt, nets, dosing bottles, fish food, spare media and spare equipment, etc. All these little things are very important. And neatly brings me on to...


Well obviously the water needs salt! Firstly use RO water, this specially filtered to take out impurities, if you have a large tank I would recommend buying your own RO unit, it will end up cheaper in the long run. But if you have a nano, then you can easily get by, getting RO water from your local fish shop (LFS). A good brand of salt is essential, to buffer the water, and add minerals such as calcium and magnesium. Your salt levels are measured in specific gravity (or salinity but not many people seem to), it should be at 1.024-1.024 at all times. Salt levels can swing dramatically (especially in nano (120 litres and less) aquaria) if you have lots of evaporation often caused by hot weather or metal halides. So a top up system is a good way forward for tank owners with lots of evaporation, this is basically an external body of fresh RO water, which is dosed in to a tank by a dosing system.

Testing... 1, 2, 3

You can test for a whole range of things, even weird things like boron! To test for these things (apart from temperature) you need test kits, which are usually liquid tests involving test tubes, or dip tests, the prior are more accurate, however the latter is a good cheaper option, but not always as accurate. Or you can get special electrical gadgets, but these are pretty expensive! As I mentioned earlier you will need to test for nitrate, nitrite, and ammonia. There are other things you must test for, temperature (via thermometer), salinity/specific gravity (salt levels, see above) and Ph. Ph is how acidic or alkaline something is, sea water is alkaline, and needs to be between 8-8.4. Decent salt (see above) will buffer your water usually, but sometimes you must buy a buffer to do it, especially as your aquarium ages.


There are loads of other gadgets out there for marine fish keeping and reefing, however the average beginner aquarium doesn’t need one. These are things like calcium reactors (used to put back in calcium which is removed by hard corals), phosphate reactors, nitrate filters etc.

The Tank

Well you need something to put the equipment in!

Size does matter

The bigger the better! Water is much more stable when in a larger quantity, so there for more easier to maintain. Generally 120-200 litre aquariums are a good size to start with, its big enough be stable, but small enough to not be too expensive. If you can fit a 200 litre aquarium, then don’t be scared to start with something smaller, the minimum I would consider starting with is a 60 litre aquarium, anything under that then you may have major water parameter fluctuations if you’re not careful. I would recommend looking at fish in your aquatics and online, seeing which ones you really want to keep, then multiply that fish’s body length by 6, that is the minimum length of the aquarium this fish needs, multiply by 2, or preferably 3, for the minimum width needed. So a yellow tang (Zebrasoma flavescens) can get to 20cm so there for need a minimum of 120cmx 40cm tank, however 60cm width is much more recommended! However this doesn’t count for eels, since they are very long yet quite inactive, so don’t need a full 6 times swimming length, as they won’t use it like a surgeonfish would, and it doesn’t work for very small fish, and doesn’t mean you can keep a trimma goby(Trimma sp.) (grows to around 3cm long if that) in a 18cmx6cm tank!

Specifically reef tanks, plug and plays, or a blank ‘canvas’?

(E.g. Orca nano, juwel lido, or clearseal?)
You have three main choices when picking a tank:
• Specifically reef plug and plays- these are tanks designed to be used for marines, usually they come equipped with the major equipment, however most people change the filter media for more suitable, and better stuff, (such as remove bio balls and using live rock instead, see filtration chapter) and most people add a power head or two. On offer for you are the Red sea max, Orca nano, D-D nano cube, River-reef nano, Aqua medic, Tunze, etc the most popular is probably the orca, just shop around and see which is right for you. These are probably the best for beginners, as they are pretty well equipped, and easy to get going.
• Plug and plays- These are tanks usually used for freshwater fish, however they can be converted. But you would have to change the lights, the filter media, and add power heads, protein skimmers etc. But sometimes it can be hard to add equipment due to hoods, so some plastic hacking is often involved. There are a lot of these aquarium ranges on offer for you, such as Aqua one, Juwel, and Rena. These are pretty good, but there’s lots of modifications you have to make to turn them in to a marine aquarium.
• Blank ‘canvas’- These tanks are just that, tanks, nothing else. These are usually preferred by reefers who want to make a tank for exactly they want! These are very good choice for more experienced aquarists, however as a beginner you aren’t used to all the equipment, and it would truly be jumping in to the deep end, and I would only recommend trying it if you have experienced fish keepers (on a forum or in real life). There are a few places you can get these, such as Aquarium Manufacturers, Aquarium Accessories, UK and many other sites. You can get the tanks with backgrounds, or get them drilled with a weir (for a sump), with a hood and cabinet, depends what your after! And you can often get whatever size you want!


Most tanks are rectangular, or cube. These are generally the best shape tanks to go for, as they have good surface water to volume ratio, and give good swimming space. There are some tanks on the market which are orbs, or columns’, or just tanks which are taller than they are deep and long. I wouldn’t recommends these, as it give you less space to stock, due to the light has to go further, and it has little volume to surface area ratio. It just makes it harder than it needs to be!

Setting up

Now you have you have got the gear, you can get going!

First things first

So where do you start? Here’s a basic step by step run through.
1. Put the tank up; add the equipment in suitable places. Put the heater near to the bottom, horizontally, and ideally below a pump. Put the power heads on the side of the aquarium, one on either side if you have two.
2. Clean the inside of the tank and equipment to get rid of dust.
3. Fill the tank with RO water, check for leaks
4. Switch all the equipment on, and add the salt to the manufacturer’s advice.
5. Let the water warm up and all the salt to dissolve, and measure the salt levels, Ph, and temperature.
6. Once all those levels are perfect, and have been for a couple of days, you can add the CURED live rock! (non cured live rock doesn’t have life on it) (later I will talk about aqua-scaping, and rock safety)
7. Then you can pour in the sand! (live sand is good, but pointless as it will become live in time anyway, use coral sand or aragonite sand, just generally only use sand which is designed for marine fish), and the top back up with the water you siphoned out earlier.
8. Once you have added live rock and sand, before adding any living thing you MUST let the tank cycle! This links in with the biological filtration part. Basically once the cycle is complete, your tank will have nitrifying bacteria in it (remember them from the biological filtration section?). If you were to put a living thing in there straight away, it would release ammonia, but that ammonia would stay there! And most likely kill the inhabitant. So how do you cycle the aquarium? In a marine aquarium this is pretty simple, when you transport the live rock, some of the life will die, and this dieing matter will release ammonia in to the tank. There will be some nitrifying bacteria in there, in the live rock, already. So some of that will exchange it to nitrite, and more bacteria will grow, and grow. You will notice a peak in your ammonia readings, and then the ammonia will fall. Then you will notice a peak in your nitrite readings, and then they fall. It is important to keep the Ph, salt levels, and temperature stable, so to not kill the bacteria. You need to test very often during the cycle (every day or two) as well to monitor nutrient levels. So when both ammonia and nitrate are 0, you should do a water change, as you may find your nitrates will be high. Then you can add your first critters! (more on live stock soon)


Before we get down to the arty stuff, you should try and follow a few guidelines to make sure you aquarium rock structure is safe:
• Place your rock on egg crate, so there are no pressure points on the glass.
• Make sure you put rock in before the sand!
• Stick the rock structure together with something (either something like milliput or on a pipe), so they don’t fall over!

So now to the more arty stuff. There are two main ways to go about scaping, ones way is planning what it will look like, and the other is getting your rock and then just put it together on the spot. Different things work for different people, but if you really want a good scape, you need to plan!
Unlike in some planted tanks marine aquarium scaping is really about replicating nature, and in my opinion a slope from one side of the tank to the other or a hill in the middle really isn’t that natural and just looks pretty boring. Two hills looks better but still isn’t that impressive. But one of the best ways to make a tank look natural is to not have rock touching the back or side of the tank, so that the scape is say in the middle (or towards the back a little more) of the tank, but not against the wall. This means that fish can swim all the way around the rock, and corals can disappear behind the rock, this makes us think there is something behind and beyond it, therefore doing its job as replicating a real reef! To help you recreate these hills, you can make egg crate shelves, or base rock, so that it bulks it up some more, the best base rock is almost live rock, but it is not as porous, so doesn’t carry as much life and doesn’t have such a big price! Also dead live rock can be great, as it will eventually turn in to ordinary live rock!

Some of the best scapes I have seen are based not on large hills and mounts, but on pipes! These scapes are basically rock which is attached to pipes, so you can make towers, bridges and a whole intricate scape! So how do you do it? I don’t know either so I contacted a friend called Anthony, who has a brilliant aquascape based on this technique, and asked him how:
What sort of rod or pipe can you use?
“I used domestic overflow pipe, the same pipe that was used for the sump return pump pipe & spraybar. As you know I also drilled this pipe (*with numerous holes) and connected a pump (in my case an external filter) to it to give flow directly onto the rock (*to aid biological filtration). This also helped with keeping the frame in position, as otherwise a sealed plastic framework would be very buoyant until the rock was attached. You could use any plastic piping for this as long as you take into account:
A. the weight of the rock, so make sure it's strong enough.
B. the fact that you want to hide the pipe, so nothing to big.
C. whatever material you use is fish-safe..”
How do you attach the rock to the pipe?
“I used plastic cable ties to attach the rock to the pipe. This was done by drilling a small hole through protruding sections on the back of the rock. Position the rock first, put your finger where the tie needs to go, and drill it.”
Is there anything special required to drill live rock?
“I used a 7mm standard masonry drill bit. I drilled the rock under water with a long bit so as not to affect the 'living' element, but a few seconds out of water probably wouldn't harm it too much.”
Anything else we should know, in general?
“Just make sure the whole thing is stable, as it will have a lot of weight on it. You will need some sort of 'foot'. I built a square section of pipe at the base of each end for this.”
Any tips?“Don't glue anything until your absolutely sure your happy with your design and the whole thing is fully built. You'll be amazed how much tinkering can be involved”
*Authors notes
Here is some pictures of his aquascape before rock and after



You don’t have to construct whole scapes using this technique, just making pillars, arches and other interesting things will add extra interest to a plain old hill.
Try to add arches, bridges, and lots of caves to you aquascape, this will not only make the tank look more interesting, but it will enrich the fish’s live by having things to hide in, sleep in, and swim through!


Before we get on to the good stuff (stocking!) you have to know how to maintain the tank first! Here is a list of the general maintenance which you need to do, excluding feeding the fish:
• Water changes, 10% every two weeks is sufficient, and even monthly water changes would be ok in a low stocked tank! However I feel to maintain optimum water chemistry a 10% water change ever 2 weeks is good (in the average beginners set up) (if you over filter you could get away with less). We water change not only to reduce nitrogen compound levels, but also to replenish trace levels, such as calcium, iodine and magnesium. Don’t forget the water you add must match up to the current tank water (in temperature, salt levels, and Ph)!
• Topping up, I touched on this earlier; water inevitably evaporates, so to keep the salt levels constant, you must top up, with unsalted RO water! Basically mark on the tank some how, how full the tank is at optimum salt levels, then is you notice the water go below this line, top up with RO until it is at the line again, this may have to be done daily. If you can’t be bothered to do this your elf then you can invest in a auto top up system, which does the work for you!
• Replacing light bulbs, fluorescent tubes need to be replaced every 6 to 8 months to make sure you have the optimum light spectrum, if you do not do this you may find your corals start to not do as well, but unwanted algae does very well! The change in spectrum may not be visible to our eyes, but it does change! You also need to change metal halide bulbs, you need to change these every 8 to 12 months.
• Other things may need to be done according to manufacturer’s instructions, you must keep up!
• Testing and checking, test for all of your parameters at least once a week, and temperature daily. Every day you must almost check that all the equipment is working properly, and that all of your stock is present, eating and healthy!
• Algae cleaning, you may think, do you have time to clean the algae? Well yes you do, because if your set up is just right, you may not have to do it at all! As long as you don’t over stock, don’t over feed, and have enough filtration, you shouldn’t get that much algae. The stuff which you do get is most likely going to be on the glass, and to clean this of it is very easy, simply buy a algae magnet, one side of the magnet sits on the inside of the aquarium, the other on the outside, so you can rub of the algae, with no wet hands! The last thing to any good algae attack scheme is a clean up crew (CUC), which comprises of invertebrates (or fish in some situations) such as snail and crabs. These animals will eat left over food and east algae, and even stir the sand for you (if you don’t have sand sifting CUC you must stir it with a stick or something similar yourself at least every week).
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