Into the Forest

(Unedited version)
Originally appeared in the March 2005 issue of
Tropical Fish Hobbyist Magazine

Last month I told you a little about the history of the planted aquarium and some of the different styles of planted aquarium that are popular today. This month we'll start looking at plants.

What exactly is a plant? For the most part this seems like it's a simple question, and for larger organisms it generally is but for some of the smaller ones it can get confusing. Even the scientific experts don't always agree on how to classify everything, and sometimes with the passage of time and more knowledge gained those classifications change.

Plants and the other photosynthesizing organisms I'll be discussing are similar in that they all can create their own food by utilizing the energy of the sun. All other animals and living things have to get their energy from eating something else. We can't make our own. The photosynthesizers keep the rest of us alive by giving us oxygen and creating our food. The plant like organisms that we will be dealing with in the aquarium are cyanobacteria, algae and plants. I'll try to tell you a little bit about all of them without getting too technical.


Cyanobacteria are often referred to as blue-green algae though they can range in color from blue-green, black, brown, purple, yellow and red. Cyanobacteria used to be classified with algae and plants. They can photosynthesize and produce oxygen like plants and algae, but they are very different organisms. Cyanobacteria, like bacteria, are prokaryotes. To simplify this a great deal they have different cell structure. Algae, plants, animals, the forms of life we as people are most used to seeing all are eukaryotes.

Cyanobacteria have been around for a very long time, at least 2.5 billion years. They may have been the first organisms to release oxygen into the earth's atmosphere. There are thousands of species living today. In the aquarium cyanobacteria are considered a nuisance. Though several types can show up in the freshwater aquarium the most commonly seen there are velvety in appearance and dark blue-green in color and have a peculiar musty smell. A common way to get rid of cyanobacteria in the aquarium is to use fish medications for bacterial infections that contain erythromycin. This can work well for the short term or occasional brake outs, but should not be used in place of good aquarium maintenance.


There are many types of algae. Though a few may be considered advantageous for the aquarium, most are the worst enemies of the planted aquarium hobbyist. Although most algae are very tiny and consist of a single cell, it can also be multicellular like hair algae, or even very large like kelp. The well over 20,000 species of algae are divided into 7 basic groups called phyla. They are the dinoflagellates (Dinoflagellata), golden algae (Chrysophyta), diatoms (Bacillariophyta), euglena (Euglenophyta), green algae (Chlorophyta), brown algae (Phaeophyta), and red algae (Rhodophyta).

4 of these types of algae aren't a reason of concern for the planted aquarist. Dinoflagellates live in freshwater and marine environments. They make up a large part of the phytoplankton in the oceans. Golden algae are so called because of their color and live mostly in freshwater. Euglena and related organisms are green and usually in fresh water. Euglena is sometimes cultured as a fish fry food. Brown algae are all multicellular and found in marine waters they include the giant seaweeds like kelp.

Diatoms do show up as a nuisance in the aquarium sometimes. They live in both fresh and salt water environments. They show up as a brown scum. It can feel kind of oily if rubbed off with bare fingers. It's usually not a problem in the planted aquarium. If seen it would most likely be in the initial set up and cycling of the tank, and will usually fade away once the tank is established and running properly.

Most of the red algae are multicellular and occur in the oceans, but there are some types that can occur in the freshwater aquarium. These are most commonly referred to as black beard algae. Black beard algae, like the name implies is very dark and fuzzy. It can be difficult to get rid of.

Green algae are the ones most commonly found in the aquarium. There are more than 7000 species mostly living in freshwater, though some are marine. These are the light green algae that's easy to wipe off the aquarium glass, the floating algae that makes green water so tank visibility is about 1/2 inch, the hard dark green algae that coats rocks and decorations and the horrible hair algae that can create mats of mess in between the fine leaves of the prized aquarium plants. Green algae are more like plants which are believed to have evolved from green algae.


Plants started coming out on to the land about 425 million years ago. Aquatic plants are believed to have first developed out of the water and then come back into it. The first types of plants to live on the land were the Bryophytes which have 3 major divisions (plant people use the term division for the major groups in the kingdom, instead of the term phyla). These include the mosses, and liverworts. Mosses generally lack vascular tissue. These tissues form tubes that transport water and nutrients in higher plants.

There are several mosses that are popular in the planted aquarium. They are generally easy to grow, have low light requirements, but tolerate a wide range of light levels. Mosses can be used as ground covers or grown over rocks, or branches in the aquarium. The most 3 commonly see aquarium mosses are Java moss (Vesicularia dubyana), Fontinalis (which may be one or more species of this genus), and Christmas tree moss. Christmas tree moss has a name problem. First of all this is also a name given commonly to several terrestrial mosses that grow upright looking like small pine trees, it's also a name sometimes given to a type of club moss that is sometimes sold as an aquarium plant, where it will not survive. The moss currently most referred to in aquarium plant circles under the name Christmas tree moss, was introduced in the Takashi Amano "Nature Aquarium World" Books. This moss is similar in appearance to the Java and Fontinalis mosses, but has a more full appearance and branches out in a Christmas tree pattern. It also tends to have lower growth and is often the favored of the three aquarium mosses.

The seedless vascular plants were the next to develop. There are 4 divisions in this group and these include the ferns. Ferns are represented in the aquarium by several beautiful examples. These include several forms of Java ferns (Microsorium pteropus), Bolbitis heudelotii, Marsilea quadrifolia and water sprite (Ceratopteris thalictroides). These plants are vascular but lack seeds using spores to reproduce.

The first plants with seeds were the Gymnosperms. There are 4 divisions which include modern day conifers but are not represented in the aquarium.

Finally about 140 million years ago flowering plants emerged, called angiosperms, and are in the Division Anthophyta. There are about 235,000 known species, representing most of the plants in the world today and of course in the aquarium. Though angiosperms may reproduce in other ways, they can also produce seeds.

Angiosperms are grouped in to 2 types, dicotyledons and monocotyledons. The names refer to the number of seed leafs the plants have. Monocotyledons have one seed leaf and represent about a quarter of the plants on earth, though among aquarium plants they may outnumber the dicotyledons. Palms, grasses, orchids and tulips are some commonly known monocotyledons. In the aquarium they are represented by the sword plants (Echinodorus), Cryptocorynes, Sagittaria, Vallisneria, Anubias, Aponogetons, Anacharis (Elodea), Heteranthera, Potamogetons, Najas, Mayaca, Crinum, and Zosterella, among others.

Dicotyledons have 2 seed leaves, and with over 250,000 species make up the majority of plants on earth. They are represented from beans and daisies to maple and apple trees and everything in between. In the aquarium they are represented by many stemmed plants like Rotala, Hygrophila, Bacopa, Ludwigia, Cabomba, Limnophila, Myriophyllum, Micranthemum, and Glossostigma. Other aquarium plants like the related Barclaya, Nuphar and Nymphaea (water lilies) are also Dicotyledons.

That's a brief overview of what sort of the plants and plant like organisms that can sometimes be found in the aquarium. Next month we'll start looking at the fresh water invertebrate found in the planted aquarium, including algae eating snails and shrimp.

Photosynthesis is an amazing thing. It's the way some bacteria, algae, and plants take the energy from the sun and turn it into energy it and everything else can use. As a waste product of this process they release oxygen that we and everything else can breathe. It's this process that made the earth a great place to live.

This is how it works. These photosynthesizers have special things in their cells. Mostly it's chlorophyll, which comes in two types, a and b. Chlorophyll is green and it's what makes plants green. There are other things which plants use to photosynthesize and they come in different colors, which is why some of the algae and cyanobacteria are different colors.

Anyway this is what happens, the plant takes 6 molecules of Carbon dioxide (CO2) and 6 molecules of water (H2O) and with the energy of light mixes it around like this:

6CO2+6H2O ? C6H12O6+6O2

Creating one sugar molecule (C6H12O6) and releasing 6 Oxygen molecules. The sugar molecule is the stored energy and Oxygen is what we can breathe.

Plants also take in Oxygen and release Carbon dioxide, they do this around the clock like we do, but they create so much extra oxygen during periods of light that the net affect is oxygen to spare.

Questions or Comments?

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Welcome to the Jungle | Into The Forest | The Creepy Crawlies | A Clearing in the Thicket | Algae Eaters for the Planted Aquarium
North American Natives | Why things go wrong Pt 1 | Why things go wrong Pt 2 (Algae) | Algae Eating Shrimp | Lo-Tech Tanks
Welcome to the Fish Room | The Stemmed Plants | Mosses | A Livebearer Biotope | Planted Tank Social | The Genus Hygrophila | Cyanobacteria
Easy Plants | What I Did Last Summer | Decorations in the Planted Tank | Botany-An Introduction to Plant Biology | Botany-Anatomy of a plant
Botany-How Plants Work | Easy Rosettes | Going High-Tech | Floating Plants | Dealing with Success | Bringing the Outside In | Vallisneria
Hair Algae | Flowering Aquarium Plants Part 1 | Flowering Aquarium Plants Part 2 | Liverworts in the Aquarium | Elements of Design
Planted Aquarium Maintenance | More Mosses | Invaders | Ferns in the Aquarium | Setting up a Planted Aquarium
Seaweeds of the Pacific Northwest | Proserpinaca | Hardware for the Planted Aquarium | Rotala | Neocaridina Shrimp | Lo-tech Tank Tips

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