Natural Aquariums
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from FishNet May 1996

I started converting my aquariums into natural aquariums about 15 years ago. I started cutting down on my equipment usage and adding more plants to my tanks, which gradually started to support the plant life. I now regularly must thin my tanks due to excessive plant growth. Now I am experimenting with other organisms to share the tanks with fish. I believe in starting simple and have been working with gammaras and daphnia lately with some reasonably good results.


There are several reasons why I enjoy natural aquariums as opposed to those that are mechanically filtered. I find the equipment to often be distracting from the beauty of the tank. I'm interested in the interaction of different factors that make up a living system. I know some people really like to play with all the aquarium equipment and that's OK if you like to collect equipment. I prefer collecting different types of plants, fish and invertebrates to go in my tanks.

I realize that trying to create an exact replica of an entire specific naturally occurring ecosystem is unrealistic. The three most obvious reasons why this isn't possible are: 1)The sheer size difference and the incredible amount of influence the land surrounding the native waters has on it can not be duplicated at home. 2) The difficulty for a home aquariast to acquire a large sample of the life that inhabits these waters. 3) Contamination from local sources.

I think that it is possible to create naturally interacting systems for aquariums and that is what I'm trying to do. Any trip to healthy local waters, creek, river, pond or lake, will reveal it to be teaming with life. In aquariums though it seems that anything other than the specific plants and fish selected are not desired. I think they should not only be desired but promoted. Small insects and algaes will consume wastes in the aquarium and provide food for fish and fry. With a more diverse community of consumers I think the aquarium is more able to withstand slight imbalances.


I find that is wise to plan an aquarium before investing in any part of it. The scheme may change over the course of time but having an idea in mind from the start helps avoid making costly mistakes in the end.

A natural aquarium may be started with a tank or bowl, gravel, and plants. I've tried various types of lighting from all sunlight to combinations with fluorescent and all fluorescent. They all have various advantages and disadvantages. With natural sunlight some very impressive plant growth can be achieved and it seems to better encourage the invertebrates. Care must be taken though to watch for possible algae explosions and over heating. This works well for fish like common anabantoids, livebearers. Fluorescent bulbs are easier to control but can be expensive, depending on what sort of fixture is needed, and it is harder to get good intensity.

I've never been too particular about the aquarium gravel. Pretty much anything I've purchased has worked. I don't use additives in the soil, I find that the fish waste and water changes provide enough nutrients to allow growth in most aquatic plants

After setting up a tank I like to add fast growing, easy plants first. I like to hold off on adding plants like Cryptocorynes and Anubias until the tank is well established. For the most part I leave the snails alone and they seem to leave the plants alone. Snail populations seem to stay at a steady rate. I have Ramshorn, Common Pond and Malaysian Livebearing Snails.

If small fish are being kept another animal that is helpful is the ghost shrimp. This shrimp, usually sold as a feeder, eat cleans the gravel surface and also will eat hair and beard algae. They can't eradicate a huge mess of it but can keep it from starting, and control small growths. Unfortunately anything bigger than a guppy will eat the snails so they are only practical in some situations.

Water changes are necessary in Natural Aquariums just like any other. At least 25 % of the water should be changed monthly. The smaller the tank or the more crowded it is the more the water needs to be changed. More frequent water changes are also desirable.

I don't use heaters in my tanks, but I live in Arizona where it doesn't get cold. In cooler climates I think they may be needed. I use no filters on any of my tanks. Occasionally when cycling a new tank, or if an established tank gets out of balance I will use an aerator for several weeks to a month or so, on a tank. I also keep a marine tank and always run air into it.


When it comes to choosing plants for an aquarium of any kind the key words are "Buyer Beware!" Many plants are sold as aquarium plants that aren't and will eventually die in the aquarium. I've seen dried ferns, spider plants, small palms, and philodendrons, among others, offered as aquatic plant. My advice is to buy a good aquatic plant book and don't purchase a plant unless you know what it is.

Many aquatic plants will have some leaf loss after purchase, Aponogetons and leafed stemmed plants seem to be most prone to this. New plant growth will likely be different than that of the plant purchased. Many plants are grown emersed (out of the water). They are also generally grown in sunlight. Different lighting can drastically change the look of a plant.

I've tried a number of different plants and liked different ones for different reasons. Following is a list of the plants I've tried with some success and some notes on them:

Anubias nana - A very nice but slow growing low plant. Like Cryptocorynes Anubias will melt if water quality or even more important the quality of the gravel becomes poor.

Aponogeton crispus - This is an easy to grow plant. It grows from a bulb and, like most Aponogetons can be purchased either as just a bulb or grown out as a plant. A. crispus will bloom readily in the aquarium and sometimes the seeds can be grown. The blossom stem is rather delicate and easily damaged. This plant will grow in almost any reasonable conditions, including lower lights.

A. madagascariensis - This interesting plant often does not do well for Aquarists. I've had one for a year and a half that has never died down and does very well. I started mine as a bulb.

A. ulvaceus - An attractive bright green plant. Not quite as hardy as the A. crispus, still, it's not difficult to grow. The A. ulvaceus grows slower than the A. crispus and is not as likely to bloom.

Barclaya longifolia - This is an attractive reddish brown bulb plant. It requires strong lighting.

Ceratophyllum demersum - Commonly called Hornwort, this is an old standby that will grow in almost any conditions. This is a fast growing plant. In lower light it is somewhat thin and bright green. As light intensity increases the plant gets bushier and in high light turns red. A very good plant for hiding livebearer fry. This is a floating plant do not try to root it. Pieces placed in the ground will die, the rest of the plant will float back to the surface.

Cryptocoryne wendtii - I have been growing both the red and green varieties of this plant. It is generally easy to grow and can grow well in lower and higher light levels. In lower light the plant will be long and thin. In high light the plant stays more compact and leaves spread horizontally over the gravel. Colors become more intense with higher lights also, in the red variety the leaves become a dark almost purple color.

Echinodorus amazonicus - Easy to find and a great and easy to grow plant. The Amazon Sword plant will live in almost any fresh water aquarium. It's a very hardy and adaptable plant.

E. bleheri - Another commonly found sword plant with more narrow leaves than the Amazon and slightly smaller.

E. cardifolius - This plant takes on a whole new look at different times. When purchased it usually has melon shaped leaves on short stems. These are accomplished by emersed growth. In the aquarium it will take on one of two forms depending on your tank setup. In the winter mine have soft long stems and the leaves float like lilies. In the spring and summer in an open ten, mine grow leaves above the water surface on long stiff stems.

E. tenellus - This is the Pygmy Chain Sword. It is a small sword that will grow over the bottom of a tank.

Egeria densa - Anachris, another old standby that is hardy and adaptable. This plant will also probably take on a different look in the aquarium than when purchased. Most offered for sale are very dark almost brown and quite thick. In the home it will generally become more green and depending on the light level may thin.

Eleocharis acicularis - Hairgrass grows best in good light. It does look like a thin bladed grass, but without lots of care it tends to grow across the top of the tank. Another good plant for fish fry to hide in. I like this one with anabantoids and livebearers.

Hygrophila corymbosa - Sold as giant Hygrophila, this plant often looses some leaves when transferred into an aquarium. New growth is generally smaller leaves. Otherwise this is a hardy plant in bright light.

H. deformis - Water Wisteria has many leaf forms and plants can vary widely in appearance depending on where the plant is grown. Wisteria grows better with bright lighting. Stems are delicate so extra care must be taken when planting, or the bruised stems will wither and the plants will float.

Lemna minor - Duckweed is a common floating plant that really will grow like a weed. It is handy to have around though. Many fish like to eat duck weed. It also is a good cover for a tank when it needs some shading, and many anabantoids like it to include in their nests.

Limnobium sp. - Frogbit looks like a large version of Duckweed. It is often sold for ponds but can be used in an aquarium too. Frogbit does need strong lighting though.

Microsorium pteropus - Java Ferns are an attractive epiphytic plant. Grow them on rock or wood. This plant reproduces by stem cuttings or from small plantlets that grow on the leaves.

Myriophyllum aquaticum - These are a very fast growing lacy stem plant. It can be grown in moderate to bright light. The biggest draw back I find to this attractive plant is it's need of constant pruning. It is another good plant to use with fish fry.

Nymphaea sp. - These are often sold as bulbs, sometimes plants. These are a water lily. Many have a lot of red color in the leaves. They are easy to grow and will even grow in low light levels.

Rotala rotundifolia - An attractive easy to grow stem plant. Will grow in moderate to high level lighting. It does take on a pinkish tint in brighter light.

Sagittaria subulata - This is a medium to low plant, which will reproduce by runners. It tolerates low light levels but needs good lighting to reproduce

Vallisneria gigantea - This means gigantea. I pulled 44 inch leaves on these plants from a ten gallon tank. Vallisneria, like Sagittaria produce by runner. They are very fast growing and need to be thinned regularly.

V. spiralis - This is a common plant, when I think of an aquatic plant. these come to mind, I think this is the most often illustrated aquatic plant. It's a fast growing plant. I recently pulled 80 plants from a five gallon hex tank.

Vesicularia dubyana - Java Moss is a lovely moss that will creep over an entire aquarium. Another good plant for fish breeding.


I have kept a variety of fish in natural aquariums for years and have bred several. I started out as a livebearer enthusiast. I still enjoy many of the livebearers. Many of the more common fish are quite suitable fish for natural aquariums and seem to enjoy the lush plant growth. Among those I would recommend are Poecilia reticulata (Guppy), Xiphophorus variatus (Variegated Platy), Poecilia sphenops (Molly), and Xiphophorus helleri (Swordtail), a not so commonly seen but very hardy livebearer is the tiny Hetrandria formosa. All will reproduce freely in this kind of environment.

Also I have had good success with breeding and raising fry of the labyrinth fish, Betta splendens (Betta) and Macropodus opercularis (Paradise fish). I have recently started keeping several kinds of cichlids, some of which have already spawned.

Other fish which I have kept in natural systems for several years are Acanthophthalmus kuhlii (Kuhlii Loach), Brachydanio frankei (Leopard Danio ), Brachydanio rerio (Zebra danio), Brachygobius xanthozona (Bumblebee Gobie), Corydoras aeneus (albino catfish), Corydoras reticulatis (Reticulated Corydoras ), Gobius sadanundio (Knight Gobie), Hemigrammus armstrongi (Brass Tetra), Paracheirodon innesi (neon tetra), and Tanichthys albonubes (White Cloud Mountain Minnow).

Natural aquariums are not suitable for every type of fish. I don't think that any difficult fish should be included in natural aquariums until the fish keeper has really explored the requirements of the fish. Some fish that only are happy in strongly moving waters or fish that are plant eaters and diggers may also not be appropriate for natural aquariums.

Thank You for coming. I do believe that natural aquariums are a very real option for many common tropical fish. Any one from beginners to advanced aquarists should be able to set up and enjoy such a tank if they follow a few simple guidelines and trust in their own judgment concerning the fish, plants, and the health of the system.

I gave this lecture on the FishNet Forum on Compuserve in May of 1996.

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