Topic 6 - Livestock
This is the last of the topics that will form the basis of starting a marine aquarium bio-tope.
There is an endless list of biotopes that you can build up, much depending on personal taste and budget. Since personal taste is very subjective, all I can provide will be guidelines on dos and don'ts, with an occasional recommendation. But whichever biotope you use, there will usually be a standard list of organisms that you will want to have, partly to upkeep your tank for you. These are the "Bandaraya" or "Municipal" creatures
For diatom or algae control, you can use the algae blenny, Salarias fasciatus. This looks a lot more cute than the freshwater plecs, and doesn't grow as large. Some of them will even take pellet and other food, when it runs out of diatoms. Be careful when you want to put more than one. Most of them will chase and bite (suck??!!) each other as they are quite territorial.
The bicolor-blenny (Ecsenius bicolor, I think) also eats some diatoms, but it prefers aquarium food!! Other than these fishes, you can also consider snails like the Turbo, Astrea and Trochus. Some people (like me!) have tried Nerites before, but they like to climb above the water line, and most will end up in your hall, bedroom, wherever! Trochus snails will multiply in your tank as long as you have a bunch of them (say, 6 or so, to be sure). In no time at all, you'll see mini trochus crawling around your tank.
Certain fish in the bristletooth family (related to Tangs) also eat diatoms a lot, like the Striped bristletooth, Ctenochaetus striatus. However, they seem to be able to recognise the algae blenny as a competitor, and usually chase them all over the place. The blenny doesn't mind, since he's so streamlined and can slip into any hole he likes anytime
Lastly, certain sea cucumbers (cukes) will also eat diatoms for you, especially on the sand bed and LR. Be sure to get sand-sifting and NOT filter-feeding cukes. The filter feeders are extremely poisonous, e.g., the Sea Apple, if they die in a power head or by other means. Some of you out there will have 1st hand experience of this. These cukes can be recognised by having very fancy feeding mouth parts like tentacles that stick up in the air. The sand-sifter cukes just look like a cucumber or banana or .....
Quite disgusting looking, but useful.
For hair algae control, you can use rabbitfish or foxface (genus Siganus) or the ever-popular tangs (family Acanthuridae). The tangs however are very choosy, and normally do not eat hair algae longer than 1 inch, while the Siganids will. In the wild, you will see schools of large rabbitfish gobbling up hair algae wherever they pass.
Some sea urchins will also consume hair algae when they crawl over the LR surface. There are however several problems with urchins :
a) They may accidentally poke your corals
b) They may knock over your LR if you haven't mounted them securely
c) They normally eat the coraline algae at the same time as the hair algae, leaving white patches.
For scavenging on uneaten food and dead fish that you can't reach deep within the LR structure, you can use a variety of shrimps. The most popular are the boxer or Coral Banded Shrimp (Stenopus hispidus) and the cleaner, skunk or doctor shrimp (Lysmata amboinensis). The boxer shrimp can be a bit aggressive sometimes towards the cleaners. The cleaners serve another function in the tank - as long as you have more than 1, they will ALL get pregnant even at the same time, and produce babies which will serve as zooplankton for your corals and filter feeders like featherduster worms.
Note: In many LFS, the holding tank water is usually of a lower salinity, sometimes even down to 1.018; When you add invertebrates to your tank, you will have to condition them slowly to your tank water first. However, this is also a good practice even for fish and corals. Most people just float the plastic bag in the tank to let the temp. equalise, but this is not enough for inverts. They have to adjust to the different salinity slowly. The easiest way to do this would be to slowly drip in your tank water into the bag. When it's quite full, pour away some of it, and continue, until both tank water and bag water are the same salinity. Then your livestock will stand a much better chance of survival.
For some fish like clownfish (especially the common or ocellaris clown), they're very susceptible to what appears to be fungus/velvet and slime on their body. A good but slow way to condition them is to use hyposalinity. This is usually done by having a quarantine tank with a simple filter - can even be sponge and carbon, since you may have to change water regularly if NH3 and/or NO2 build up fast. Don't worry about NO3- or KH here.
Basically, you need to lower the salinity from the LFS water daily for about a week or so, down to 1.009, but since most of our hydrometers are not very accurate, target 1.010 - it's a lot safer. Once it's reached 1.010 keep the fish there for about 2 weeks. This will be enough time for most external parasites to drop off and "burst" in the lowered salinity. Then start changing water to bring the salinity back up to your main tank salinity, but go even slower than the 1st time. Once in the 2 salinities are the same, ensure that the temperatures are the same too, and place your fish into the tank.
Biotopes :
Fish only - totally up to you - could have a genus tank, with fishes of the same genus like yellow tang, sailfin tang in the Zebrasoma genus, or say a tank of groupers in the Epinephelus genus. You could also do a mixed predator tank of lionfish, moray eels, groupers. Of course, you could keep it simple and have a Amphiprion tank of only clownfish, and even try to get them to breed! For large tanks and impressive fish, many people like to keep angels from the Pomacanthus or Holacanthus genera. Very challenging and quite expensive, but worth it in the end. For a low bio-load and stable environment, try to have no more than 1" of fish for every 5 US gallons of water.
Reef - again totally up to you, but basically try to avoid putting angels and butterflies into this biotope. Most of them would love to take a bite at your corals. If they happen to like it, that coral is gone... kaput ... finito. You can have a community of different fish in a reef tank, and many people like to put damsels in - colourful and cheap. Only problem is, they're sometimes bullies, and it's 99% impossible to catch them in a reef tank.
You can have specialised reef biotopes as well, for instance a shallow-water high-energy setup where light is intense and currents are strong, for SPS corals like Acropora, Montipora, Poccilopora, Porites, etc. Or a calm lagoon biotope with mushrooms, buttons, brains, LPS corals like bubbles, hammers, frogspawn, etc. Or a mid-water high-energy setup with only soft corals instead of SPS corals. Or a gentle hill slope of LR containing only plate corals of various colours. Or an anemone tank with the correct clownfish species in them. A very good mix would Stichodactyla haddoni and the saddleback clown, Amphiprion polymnus, or perhaps the bubbletip Entacmaea quadricolor with a maroon clown couple.
Then again, 90% of reefers keep total community tanks. Typical case would be most LFSs themselves. Their tanks are usually packed solid with corals next to each other, so much so that you can hardly see the LR structure
This is definitely NOT the case in the wild. Like fish, corals will also grow and they have nematocysts (stings) that they will use against their neighbours. Some also have toxins that they are very willing to release as well. If possible, try to keep at least a 6" diameter of space between each coral. Of course this means that in a nano-tank, you can probably only have 2 pieces
Coral placement : Most corals do not like being in the path of a full blast of water from a powerhead. They need water flow, but not too violent. You can always turn the powerhead somewhere else to change the flow, or change the position of the coral, or use a piece of LR to deflect/diffuse the water flow a bit. Certain corals do better on sand beds, while others do well on rock surfaces. Plates (Fungia, Heliofungia) and brains should be placed on the sand bed. Most hard corals can be placed in the LR structure. Same thing with buttons, mushrooms and soft corals. These 3 groups of corals will usually stick and spread onto the LR, thus getting larger colonies.
Note : Plate corals will move slowly and if you place it on the LR, it could fall down and kill itself, while releasing thousands of nematocysts. Or it could fall on top of another piece of coral, killing itself and the coral.
Lastly, photosynthetic corals in addition to needing light should also be fed. The food to feed depends on the coral. Those with small polyps will take zooplankton (animal-based mobile), those with tiny polyps will take that and phytoplankton (plant-based, very small), while those with large MOUTHS (like brains) will take solid food and also various types of plankton. Plankton is nowadays available in dead liquid form, dead powder form and live form. If you use the dead forms, do NOT overfeed, or you may encounter hair algae problems or even cyanobacteria outbreaks. Live phytoplankton will not pollute your water and will even multiply in your tank under the right conditions.
Non-photosynthetic corals are VERY hard to maintain since they must be fed planktonic foods almost on a continuous basis. This is normally achieved by having a very slow drip system as in a topup system. These corals are normally the very colourful carnations (Dendronepthya) and the bright orange sun corals (Tubastrea). These should be left to the more experienced hobbyists that have the time and patience to maintain these corals.