The Tranquil Aquarium

I hear that jellyfish were recently all the rage in Japan. Watching the pulsating bells slowly move about the aquarium is supposed to be very relaxing; reducing blood pressure and clearing the mind. I have no doubt that this is true…at least until the jellyfish die on you. All the literature I have ever read tells me that jellyfish are almost impossible to keep. So, either the Japanese solved the riddle of how to maintain the jellyfish or the fad died out when all the jellyfish did. Considering that we are talking about the same pet industry that gave us the cyanide-collected clownfish and the dye-injected glassfish, I’m betting on the latter.

But the principle of a tranquil aquarium is a good one. A prominently displayed aquarium with slowly, elegantly swimming fishes can do wonders for your state of mind if you just take the time to relax in front of it. But few hobbyists actually set one up. Why is this? Well, the normal progression that a North American hobbyist advances through is to start out with a community aquarium with a hodgepodge of hardy fishes: this tank is too varied to be tranquil. If the fish bug is caught, the next step is to move on to breeding fishes: then the tanks become too utilitarian to be tranquil. Then, finally, breeding fish gets to be old hat and the challenge of keeping and breeding luxurious plants presents itself. Only at this stage is one likely to set up a “tranquil aquarium”.

So, what is a “tranquil aquarium”?

A tranquil aquarium is one that presents a pleasing natural view (so it must be well-planted), has gentle current (so it can not have washing-machine strength filtration), is large enough to fill the eye and allow fish to behave naturally (so 1.5m is about the minimum length), and contains a visually peaceful fish display.

First let’s talk about the “visually peaceful fish display”. The first thing we need is a single large school of fish cruising at a nominal speed. They should take at least 30 seconds to get from one end of the tank to the other. Why a single school? Well, this is to avoid the hodge-podge look that aquarium novices almost invariably get as a result of wanting one of every fish in the store. We are past that: we are now aiming for balance, harmony, and simplicity. Watch a tank with 30 fish of 15 species and then a tank with 30 fish of the same (schooling) species and then tell me which one has the balance, harmony, and simplicity.

The schooling behavior is important. Schooling fish are very relaxing to watch. The aesthetic appeal of watching fish move together in unison is difficult to describe…but it is of paramount importance when creating a tranquil aquarium.

So we want a single large school…of at least a couple of dozen fish. Of what fish? Well, I wouldn’t use rainbowfish or danios…they swim too fast. Small South American tetras are a better choice, because despite the fact they can swim at lightning speed when they want too, they usually cruise around at a pretty poky pace. The choice between one of the “round-bodied” tetras, like the bleeding heart tetra (Hyphessobrycon erythrostigma), and one of the “elongated” tetras, like the neon tetra (Paracheirodon innesi), is a bit difficult. As a general rule, the elongated tetras tend to be faster swimming but tighter schooling than the round bodies. So I would choose an elongated tetra. Although the elongated tetras are a bit quick, they move much more nicely as a group. We wish to achieve the “unison” effect of fish moving together along the length of the tank…and bleeding hearts just don’t cooperate. By the way, cardinal tetras (Paracheirodon axelrodi) are my favorite.

Also possible are small barbs, but they have the same disadvantage that round-bodied tetras have: they tend not to school too closely.

Now we wish to add a visual counterpoint to the elongated fish in the shoal: this is best done with a flattened, disk-like fish. Discus (Symphysodon aequifasciatus) work very nicely, but discus are expensive. Severums (Heros sp.) are the poor man’s discus and are a viable alternative, as are angelfish (Pterophyllum sp.) and festivums (Mesonauta sp.). These fish all have a good shape and move slowly enough for the job, but they can be a bit feisty among themselves and may regard the cardinal tetras as food (a habit that keeps the cardinal’s speed high and numbers low). Another good choice is the pearl gourami (Trichogaster leeri) if you don’t mind mixing Asian and South American fishes. Get at least six of your “disk fish”. Now add half a dozen to a dozen Corydoras catfish, and finally either get a small pleco species, like the clown pleco (Peckoltia sp.) or bushy-nosed pleco (Ancistrus sp.), or a small group of Otocinclus. We now have our fish chosen.

But much more important to the tranquil aquarium are the plants. We want a wall of gently moving green. Again, use restraint when choosing species. We do not want a “vegetable bin” display of many species, we want simplicity and visual harmony. Four species is plenty. How about a shorter foreground plant, and three kinds of taller plants? A nice arrangement would be to have Vallisneria around the sides and back, then a few big melon swords (Echinodorus osiris) in the mid-right of the tank, and a “leafy” plant like Ludwigia on the mid-left to counterpoint the strap-like leaves of the Vallisneria. Any of the shorter Cryptocoryne or Sagittaria species are good for the foreground.

Now the plants are going to need a lot of light (at least 0.5 watts per liter), and this detracts from the tranquil affect we are hoping to achieve. Tranquil lighting is subdued lighting. Healthy lighting is bright lighting. Hmmm.

We can help a lot by using dark background. A garbage bag taped to the back of the aquarium is good. And dark gravel: this is a little harder to come by but it is well worth it. But the problem with the dark gravel that is sold in pet stores is that it’s often too sharp and too coarse for good plant growth, and it is always very expensive. The problem with natural gravel or sand like Sil 7 is that it’s sand colored rather than dark. It is however cheap. Ideally we want cheap, rounded, coarse black sand; but I don’t know of any local source. This is a quandary I haven’t solved yet. I just keep dreaming of the black sand beaches in Hawaii.

But say we reached some sort of compromise on the substrate. Another thing to try is to have a dual lighting system. Have the bright lights on during the day…say from 8:00AM to 5:00PM, then have a single light on from 5:00PM to bedtime. This will give your plants the light they need but allow you to watch your fish in the tranquil twilight of the evening.

Filtration should be quiet and not very strong. A good quality canister filter is nice in this regard. They are almost silent, and do not disturb the surface unless the outlet uses a spray bar. A trickle filter can also be used if the pump isn’t too powerful and is quiet. A normal powerhead works nicely. The sound of water flowing through a trickle filter can be very soothing…just make sure it trickles rather than pours. But you will still need to turn the tank volume over at least once per hour.

As far as the tank itself goes…the bigger the better. One more than 2m long is good. Yes, I know such big tanks tend to be used for big cichlids and giant catfish…but what’s tranquil about a cichlid tank? We need something big enough to fill your eye…internal harmony can not be achieved if you still see the world’s distractions. And we want to be able to watch the school as they cruise from end to end. This won’t happen if the school is as big as the tank. And remember, a well-planted 1000-liter tank with 24 cardinal tetras, six Corydoras, a pleco, and a few pairs of discus isn’t going to need a lot of maintenance. This is a good thing since you aren’t going to relax in front of your tank if the algae you scraped off yesterday has already grown back.

A tranquil aquarium is a beautiful aquarium. A tranquil aquarium is simple to maintain. And a tranquil aquarium will do your blood pressure some good too. So take the time to set up a tranquil aquarium, and get something back from your fish. ?