Marine fish stocking guide.

We usually have several large shoals of marine fish in stock. Click the photo to see what we currently have.

THE MOST COMMON WAY TO STOCK A MARINE TANK.

Many hobbyists (especially those new to the hobby), want to just keep as much variety of colourful fish as possible. We call this stocking plan the "half a Noah's Ark" approach. Typically they'll have a pair of Clownfish, and then add 1 Tang, 1 Angel, 1 Wrasse etc. Often picking whichever fish of each type has the best photos on Google. It seems like a good way to get a wide variety of brightly coloured fish, however, it's not a good way to stock a tank.

The main problem with picking from photos is that fish that tend to not move much are the easiest ones to photo. So while fish like Banggai cardinals look great in a photo because they are fairly inactive and so easy to photograph well, they are also quite boring to watch. Having fish that are pretty to look at might sound great, but, after a short while you will become used to seeing them and they won't have as much entertainment value long term as a fish that has interesting behaviour. Also picking from a photo you are also more likely to get fish that may be incompatible with your other choices, or, may grow too large for your tank. You also end up with a tank that looks nothing like an actual coral reef, and recreating a natural reef is what probably attracted most of us to the hobby in the first place.

A BETTER WAY TO STOCK A MARINE TANK.

A far better approach to stocking is instead of choosing a selection of single fish, to instead choose fish that are much smaller, that you can then have far more of too. This way you can have just as many species as with a smaller number of larger fish, and you get to see all the interactions between members of the same species. Adding 1 large or even moderate sizes fish may sound cool, but, having half a dozen smaller fish instead will add far more colour and movement, and are far more interesting to watch.

HOW MANY FISH CAN YOU HAVE

There are many different ways of calculating how many fish to put in your tank, and each has their merits and drawbacks. I started keeping marines back in 1987, and since that time have tried a variety of different ways to calculate stocking. Over the last 30+ years this is the system I've came up with, which is fairly straightforward, and works well for 99% of the fish likely to be kept.

THE SALTY REVOLUTION GUIDE TO STOCKING A MARINE AQUARIUM.

PART 1 - MINIMUM TANK SIZE

You will see that most of the fish on our website have a minimum tank size quoted. This is not how much stocking space it uses up, but, instead is how much space the fish needs to feel secure and get enough exercise. This even applies to juveniles of that species. Juveniles are often more active than adults and in some species the babies need as much space as the adults. If a fish does not have enough space, especially growing juveniles, then they may grow in a misshapen way. For example Tangs housed in tanks that are too small will often grow in an elongated shape. Fish such as Sailfin tangs which should have a round body, will be shaped more like an egg shape if they don't have enough space as juveniles. This stretched out body style then doesn't have the right shaped body cavities inside for their internal organs to grow properly, often ending up with a premature death from organ failure. It is vital therefore that minimum tank sizes are adhered to. If it says 500 litres minimum, then it means 500 litres minimum, even for a juvenile. Bear in mind that this is also the minimum recommended tank size, not necessarily the optimum tank size. Although we quote 500 litres that is the minimum, and if you have 1,000 litres or more, then even better.

PART 2 - HOW MANY FISH CAN YOU HAVE.

Most basic stocking guides will often quote X amount of inches of fish length per so many litres or gallons, but, this isn't a very satisfactory system. Imagine fish A is 1" long and fish B is 2" long. On this system you could have twice as many of fish A as fish B. However, assuming fish A and B are roughly the same bodyshape then fish B is not only twice as long as fish A, but twice as wide and twice as tall too. So fish B is actually 8 times the bodyweight of fish A (2x2x2=8). So you can probably have 8 of fish A instead of 1 fish B. The system I've found to be best is a compromise between these two systems. So using our system this is how many fish you can have:

Step 1 - Take the total volume of water in the system including the sump, and divide by 10. This is how many stocking points (SP) of fish you can have. So on a 200 litre tank that would be 20 SP.

Step 2 - if a lot of your fish are juveniles of species that grow quickly and get much larger than they are then reduce your number by upto 1/3 or 33%. So your 20 SP could be reduced to 13.3 SP if you have a lot of juvenile fish, but, only do this for fast growing species, as your basic 20 SP number is well within safe limits and accounts for a bit of growth etc. More than enough for most tanks.

Step 3 - Roughly guess the current length of each of your fish. Judging sizes can be tricky, so compare them to a familiar object such as a 50p coin. Then try to judge how many 50p's long they are. For larger fish comparing them to a folded piece of paper is a good way to guess their size. Is the fish the size of A4, A5, or A6, paper for example.

Step 4 - Consult this chart to see how many SP each fish is. Larher fish count as more points for their length than smaller fish, due to the difference in bodyweight.

For fish 5" to 10" their SP is double their length. 10" fish = 20 SP 9" fish = 18 SP 8" fish = 16 SP 7" fish = 14 SP 6" fish = 12 SP 5" fish = 10 SP

For fish 1.5" to 4" their length is their SP. 4" fish 4 SP 3" fish 3 SP 2" fish 2 SP 1.5" fish 1.5 SP

For small fish they count as much less than their size. 1" to 1.5" fish = 0.5 SP

For tiny fish their effect on the system is so tiny you can have an almost infinite amount. Fish upto 1" = 0.1 SP.

Using this system is a far more accurate way of judging the load on the system. It also shows how by getting smaller fish than you may have planned to initially, allows you to have a lot more fish. Which is great news, and also means you can now recreate a more natural looking tank with shoals of small fish darting or cruising around. Just like a real coral reef!

STOCKING YOUR TANK.

Once you've worked out how many SP you have then to create a really natural look allocate half your SP to shoals. The other half of your SP will then be used for pairs, or, single specimens.

TANKS 100 - 200 LITRES In tanks of 100-200 litres, it's probably best to put half your total points into having 1 big shoal of something, or splitting it into 2 smaller shoals.

TANKS 200 - 500 LITRES Here you have a bit more space, and far more options as to which species you can have. Tanks this size usually look best with 30% of your total SP used for 1 big shoal, and 20% of your total SP used for 1 medium or 2-3 smaller shoals.

TANKS 500 LITRES PLUS On tanks this size to create a really natural look use 20% or more of your total SP on one big shoal, and another 20% of your total SP on several smaller shoals.

YOUR OTHER STOCKING POINTS Then use your remaining SP to add a variety of single fish and pairs.

THE NATURAL LOOK

Using our stocking guide your tank will now have one impressive shoal of fish as it's main feature. This will look spectacular, and soon grab the attention of any viewers. A closer inspection soon reveals the smaller shoals, pairs of fish, and the odd single one, all going about their little lives. It's a fantastic way to stock an aquarium and will look far more eye catching, and much more like a real coral reef than the "half a Noah's Ark" approach.

Click HERE to see which shoals we currently have in stock