Excessive growth of stoneworts can cause problems with blocked
waterways. When there is a problem with excessive growth,
finding the reason this has occurred and correcting it is the best
recommendation. That isn’t always possible, however, so other
methods of control are used. Sometimes if the problem is small, it
can be fixed with simple manual removal. Biological methods of
control often use carp species that are reported to eat both Chara
and Nitella. Sometimes chemical methods are also used to control
Chara are often called muskgrass. This is due to an odor they
produce, which becomes particularly evident if you crush some of
their branches. Most describe it as a garlic or skunk-like smell. The
Chara I have don’t have a strong odor, and I don’t notice anything at
all above the aquarium they’re in. They only have a very light odor
when I work with the plant. If I really crush some branches, it smells
like freshly crushed grass with a hint of garlic. The odor is one way
to tell Nitella from Chara, as Nitella do not produce an odor.
Chara are green to grayish green in color. They have stem-like
structures that have six to sixteen branchlets growing out in whorls
at the nodes. The branchlets growing on Chara are never divided.
These branchlets will often have very tiny thorns, which can be
seen if you look very closely under good lighting. They may give a
rough feel to the plant, but I’ve never found them to be painful to
the touch in any way.
The genus Chara was established in 1763 by Linnaeus. They
can grow in shallow to deeper waters. Unlike Nitella, Chara prefer
a more hard and basic environment, though plants from the two
genera are sometimes found growing together. Chara grow in lakes,
ponds, and slow-moving streams. Some Chara can even inhabit
brackish water areas.
Chara can become coated with lime depending on their
environment, which can give them a very gritty and sandy sort of
feeling. Chara takes calcium bicarbonate from the water and as a
byproduct of photosynthesis produces lime (calcium carbonate).
Since this stays after the algae dies, it can form large deposits over
time. This mixes with other components and creates something
called marl, which is used in agriculture as a fertilizer. This process
also can change the water chemistry over time, softening the water
and leading to a change in the entire aquatic environment. Chara
seem to be used more as a food plant than Nitella. It’s reported to be
a favorite food of many ducks, and moose also eat Chara.
Nitella is light to dark green with forked, bushy branches. The
stem-like structure is hollow, with whorls of forked branchlets that
grow in intervals along its length. The forked branchlets grow in
groups of six to eight. Larger species of Nitella can be over 6 feet
long. When compared with Chara, Nitella is softer to the touch.
Nitella can grow from shallow to deeper water, often deeper than
the flowering plants. They tend to prefer softer, more acidic waters
than Chara. Usually this plant prefers to stay near the bottom of
lakes and ponds. Like Chara and sometimes together with it, Nitella
can form large colonies underwater.
Nitella provide homes for small invertebrates and fish in the wild and
are eaten by some animals, though they don’t seem to be as favored
a food as Chara. Like Chara, Nitella is also beneficial in removing
nutrients from natural waters and helps to stabilize sediments.
If kept under intense lighting and not well controlled, Chara tends to
grow in a dense mat at the surface of the aquarium or pond.
While it has been used as an aquarium plant since the early days of the
hobby, in nature Nitella usually prefers to stay near the bottom of lakes
and ponds, where it can form large colonies.
Tropical Fish Hobbyist www.tfhmagazine.com