Aquarium On The Rocks
Aquarium On The Rocks
Written by Thursday, 03 August 2000 01:00
On the Rocks? Of course I don’t really mean aquarium with ice cubes. The word “rocks” should be taken literally in this case. I merely intend to give some guidelines and advice to those aquarists who, like me, keep cichlids from the African Rift Lakes. African Rift lakes include lake Malawi, Tanganyika and Victoria as well as some smaller lakes in the same area. The information included in this article is based partly on books I have read but mostly originates from my experience with these species (mostly Malawi mbuna and Haps). I have kept them for 5 years now and tried every possible combination in aquascaping. Strangely enough, no matter what the aquascape was the Africans did well – really hardy fish if one keeps the basic rules. However, there is only one aquascape which revealed their true behavior, their natural instincts, increased spawning frequency, reduced aggression and finally let these fish thrive. To cut a long story short, the best aquascape for these species is plain sand (too much sand) and rocks (too many rocks). If one follows this simple aquascape then success is almost guaranteed. I assume that the fishkeeper knows everything about water chemistry, water changes and feeding habits for these species and his only worry is the perfect aquascape for them.
Why rocks and sand? Firstly, because this is their natural biotope. As I always proclaim, fish keeping is both an art and a science. It is always stupid to neglect nature’s lessons. These species evolved in this specific environment for millions of years and everything they do, even the way they look, is adapted to this environment. Keeping them in anything else than rocks and sand is already “unnatural” by definition. Once I met a hobbyist who kept a Sciaenochromis fryeri (a fish with an intense blue color) in a tank with a purple (fluorescent?) gravel. Why? The answer was “Because it makes a good contrast”. Forgive me for saying that, but if this is your idea about fishkeeping you shouldn’t spend any more of your time reading this article. All of us know that the idea behind the coloration of any living creature is mainly to adapt to its background, to become less visible to its enemies (predators) or to make the predator invisible to its pray. Take a look at the photo of the sub adult female Nimbochromis livingstoni in my tank. You can barely see where the rock stops and the fish starts. Since this particular species is primarily an ambush predator you understand that rocks and sand is of paramount importance to it.
This is the idea behind it. No blue creature would survive for 5 million years over a bright pink bottom unless it was the largest, most aggressive predator around. Still it would probably starve to death since it would be visible from miles away. Secondly, these fish use these two elements (rocks and sand) all the time for their everyday needs. Malawi rock dwelling fish (mbuna), their Victorian counterparts and the Tropheus genus from lake Tanganyika are classic examples, which use the huge rocks to eat algae (or invertebrates / crustaceans that live in it), to hide or to spawn. In short, they spend their whole lives next to a rock. Keeping them in an aquarium without rocks is simply unnatural. Haps on the other hand use the sand to create their spawning pits, clean their gills, there is evidence that they even use it to digest their food. This is an element of their surrounding, which is essential for their well being – it is not an accessory, not if you are dead serious about keeping these species happy. Even if we examine the aesthetics of this combination, nothing beats it. It is a pale, neutral combination, which brings out the colors of even the dullest fish. It will not distract the eye (as colorful plants will) from the fish itself, thus making your precious fish the point of interest. It also creates the impression of the “natural” environment to the spectator. It makes your tank a “miniature” of the lake. I hope you will agree with the principle that rocks and sand is all the African cichlids from the Rift Lakes will ever need. Then we have to discuss the various issues that the fishkeeper has to pay attention to in order to create a trouble free environment.
Collecting the rocks. With rocks and stones you should pay attention to collect real rocks. Yes, it may sound a paradox but sometimes you may end up with pieces of marble or cement deposited there by humans. The best rocks are the ones, which have no sharp edges to avoid fish wounds. Sometimes your fish may need to scratch on the rocks because of the presence of protozoans in their gills. In this case, sharp edges may scratch their protective slim coat, which is the first step for all sorts of infections.You should collect rocks of various sizes but you should also take care to collect both round and flat rocks. A little planning beforehand will help you to get what you need. Make a drawing of what you intend to build and take a ruler or other measuring device with you. You must take into account the dimensions of your tank. Collecting a beautiful huge flat stone is pointless if it won’t fit in your 20 gallon tank. Another thing to consider is the weight of the rocks. On average you must calculate that a rock is 2.5 times heavier than water. If you have a household bucket with volume indications you can fill it with water, dip the rock in, take it out and see how many liters of water are missing. You then multiply this number by 2.5 and you have the weight of the rock (in Kg). You should avoid any rock which has plant matter attached on it (algae or other plants). If you plan to have a well-lighted tank the color of the rocks doesn’t really matter because they will be soon covered with algae. If you will have a normally lighted tank you should avoid the white stones (or the ones with a light color) and opt for the dark ones. The best colors are black, dark gray, dark green and dark brown stones. These colors make a natural contrast with the light color of the sand. The best stones can be found in the water or at the waterline, since these stones are washed by water and there are absolutely no sharp edges. Some stones contain a large metal content and they will leak in your tank. This may introduce heavy metals (iron, lead, copper etc.) in your tank something to be avoided at any cost. Heavy metal poisoning is always fatal to fish and usually it won’t have any warning symptoms. In order to make sure that this will not happen you should check the rocks on the spot. Choose any “vein” with a metallic color (like rusty iron) and add some drops of a weak acid (use a lemon or vinegar). If you observe any fizzling or see any small bubbles formed then this rock will definitely leak in your tank, leave it there and choose another one.
Cleaning the sand and the rocks. You will have to use buckets and plenty of water. Don’t rush this procedure; take your time. The more time you spend cleaning the sand at this stage the fewer problems you will have later on. Otherwise you will have a cloudy tank, all dust will settle on the bottom and will then reappear every time your fish stir the sand. It may also clog your filter (especially sponge filters). Use many changes of water (while stirring the sand with your hand) until the water comes out clear. With rocks you will have one step more. Before washing them you will have to scrub them with a toothbrush or a bath brush to remove any particles from their surface. Then you will wash them (separately from the sand) until the water comes out clear. When you see that the water comes out of your buckets clear it is time to move on. After the final washing you will have to disinfect your sand and the stones. You can either boil or chemically disinfect them. I do not recommend boiling sand and rocks because some times the rock may break (especially if air is trapped in a cavity). I prefer chemical disinfection with household chlorine. I use a 10% solution for both rocks and sand. I leave the chlorine solution for 2 hours and then I wash it with plenty of water. You must only stop when there is no more chlorine smell and there is no foam formed. Then you will fill your bucket with water, add 10 times the recommended dose of dechlorinator and leave it there for an additional 15 minutes (stir the sand at this point). After that, remove the water and let the sand and stone to dry completely. You should store them in closed containers until you need them. I use to store them in old travel bags wrapped in clean old clothes.
Placing the rocks in the aquarium
The first thing to remember is to add the rocks first (not the sand). Always place a piece of styrofoam on the bottom of your tank and place the rocks on them. The weight of the rocks and the sand will keep the Styrofoam in place; there is no reason to glue it on the bottom with silicone. Add some large rocks at the bottom row since the sand will cover completely small stones. Use your imagination at this point. Carefully select the stones and form steady piles.
Creating caves of variable size is very important. You must keep in mind that tiny fishes as well as adult ones will use these caves. The fry released in the tank during the first stage of their lives will use the caves. In this case the caves should be really tiny so the fry will fit in but larger fish won’t. This will dramatically increase the survival rate of the fry. As you can see in the photo, some fry will make it even in a large tank (320 gal) of predators (Malawi haps).
The caves will be also used by pray trying to escape its predator; this fish can be of any size so you need many sizes of caves. Submissive males will also use them to escape the harassing of the dominant ones. Carrying females as well as sick or wounded fish will also use them as a shelter. Finally they will be used as a day home for nocturnal species like catfishes (plecos, loaches and Synodontis species – see photo).
Using the round rocks you may create really tiny caves. You just put two round stones next to each other and let their shape work out the rest. Round stones can also be used as a support for large flat stones.
Using the flat rocks you create spawning places as well as “roofs” for your nocturnal fish (usually catfish). Indeed most haps (as well as many mbuna) will choose a flat rock to spawn. In the photo you can see a pair of Cyrtocara moorii, which spawns on a flat stone. This stone is the roof of the shelter of my Synodontis decorus.
Securing the rocks is a very important issue. Cichlids like to dig; this is why we placed the stones on the bottom. However cichlids will also grow to a large size and become powerful enough to move a stone either accidentally or on purpose. No matter how it happens, a stone, which falls on your glass, may cause a disaster. Thus we have to take some precautions. The first is to allow some space between the rocks and the glass, which will be filled by a pre-cut piece of styrofoam or a plastic rock imitation. However, this may not be enough – cichlids may work miracles. The first way to secure the rocks is to glue them together with aquarium silicone. This should be done while the tank is still empty. The silicone should be allowed to dry completely before adding water in there. I recommend one week as the minimum time for that. A second way to do things is to use screws and bolts. This is the best way to do it but requires a lot of skills, time and efforts. Unless you know what you are doing, you better forget it. The last way to secure the rocks is using cement to keep them in place. This should also be done while the tank is still empty but it has the advantage of a better look since the joints will not be visible.
Placing the sand in the aquarium. As said, the sand will be added in the tank after the styrofoam and the rocks. The depth of the sand layer should be between 5 and 10 cm. Keep in mind that sand also weights 2.5 more than water. In view of that, a 10 cm layer in a tank 2.1 m X 0.6 m X 0.6 m (7’X2’X2’”) which is quite typical for big African cichlids will weight 315 Kg (more than 600 pounds). In this case weight becomes an issue. You should keep in mind that no under gravel filter (UGF) can be used with the sand. The sand will become too packed to allow any kind of flow to the filter. On the other hand, sand can be cleverly used (with the help of stones or other material) to create different level in the tank, which is something unusual and attractive. A very important issue is to leave large open areas with mere sand. This will immediately become the playroom of your cichlids as well as the spawning place for some of them. The water should be added later (pour the water in a plate placed at the bottom to avoid extreme stirring of the sand) and you should let the sand settle before operating any filters (especially the ones that include a sponge).
Placing plants in the aquarium with rocks and sand is not really an issue. When planning your tank you should create “pots” with rocks, which will not leave enough space for the cichlids to dig (usually such “pots” should have a diameter less than 5 cm / 2”). You may use Anubia sp, Hygrophila corymbosa, Vallisneria gigantea and Cryptocorine sp. After planting them in the sand you may place some small rocks next to the roots, which will make uprooting almost impossible - although you should never say “impossible” when keeping cichlids. In more than one cases, these little intelligent creatures have managed to surprise me (usually nastily).
Maintaining an Aquarium On the Rocks. This is not difficult and should be done in large intervals only. Siphoning the sand every two months is enough. I personally clean the sand every six months (once I didn’t clear it for a whole year) and I didn’t have any problems with my fish. During siphoning the upper layer is removed along with the debris and dendrites and is collected in a bucket. After washing it some times to remove all impurities, you can safely add this sand back in your tank.
Aquascaping with Rocks and Sand is like drawing in “free form” mode. Only your imagination is the limit. The result will be a rather “dull” but natural and efficient tank, which will have some really happy inhabitants. Your cichlids will be allowed to form their territories, hide when threatened, retreat when defeated and spawn, as they like. In short, they will live a life as they are supposed to do, as they were built to do. You can also see the relevant article of Frank, on how to use really big rocks in your tank!!
NB: This article originally appeared in FAMA, January 2001 issue.
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