Algae Gallery

In principle, I've got nothing against algae. I like algae. Some of my best friends are algae. But in moderation.

When I started trying to find out what my algae were, and how to fight them, I quickly realized that not only did different people mean different things when they talked about "brush algae", "hair algae", "black beard algae", "staghorn algae" etc, there were precious few pictures of how these algae were supposed to look, and the few there were usually not of a quality to allow identification. And since it was basically impossible to determine what alga I was looking at, it was also basically impossible to come up with specific countermeasures against them.

Well, I'm gonna do my bit. As I can't ID the suckers, I'll do what I can: offer free pictures of the (admittedly few) species which pop up in my aquaria. This is an ongoing project: please mail me any suggestions or corrections you may have! The pictures are offered as public domain; see bottom of page for details if you wish to use these pictures.

If you think you can ID any of the below algae, either to common name or scientific name, please mail me!

For further help with identification of aquarium algae, also refer to this extremely good page:

For reference: My main aquarium has very strong light (Metal Halide), a pH of 8.3, very high alkalinity (I top up with limewater), is borderline brackish at 0.5 ppt salinity, and at least the phosphate levels are low; I do not know the nitrate level. The Vallisneria are suffering from lack of some nutrient, probably nitrate. My breeding tanks have weaker lighting (2x18W fluorescents), higher nutrient levels, neutral to acidic pH and low hardness. The magnifications given for photos are highly approximate.

"Bushy alga"

The first Gallery depict an almost feather-like branching green alga. It seems to like strong light, growing right below the halides, and is fast-growing. It forms loose, attached, clumps, 2-4 cm in diameter, on glass and on Vallisneria (as can be seen in the pictures), although individual strands extending into the water column may be as much as 40 cm long. They are attached to the substratum with a small disc. Clumps are quite soft but feel slightly rough, like wet cotton, and collapse almost flat when taken out of the water. It has a distinct, slightly unpleasant, smell, reminiscent of wet moss.

I believe this is a species of Cladophora. This because the cells are large; there are numerous small, oval, chloroplasts in each cell; branches arise close to a distal cross-wall between two cells; cell cross-walls form some distance from the tip. All the mails I've received concur - this is a Cladophora.

Common name: If there is a generic common name for Cladophora, I don't know it. In Swedish Cladophora are referred to as 'slick', a name which works in English too, I guess. I otherwise refer to this alga as "the bushy alga".

What eats it: Snails, especially neritids, eat it; my roaches (the fish Rutilus rutilus, not the insect) and Amano-shrimp (Caridina japonica) eat it; Otocinclus and Siamese algae eaters (Crossocheilus siamensis) do not eat it. Tropica Master Grow fertilizer (nitrate and phosphate free, but high in iron) strongly boosted growth of this alga.

Other means of fighting it: I tested if hydrogen peroxide could be used to combat this alga. I sprayed clumps of this alga with a total of 100 ml of 3.6% peroxide using a syringe, giving a total peroxide concentration in the aquarium of 20 - 25 ppm. I repeated the process daily for a total of 7 days. Day 1: violent bubbling from the algae, but no other noticeable effect on this alga. Day 2, after application of peroxide: a few clumps which were directly sprayed lost all green color. Day 3: before application all clumps had regained green color, upon application the clumps which had bleached the day before, plus some new ones, turned white. Day 4 & 5: some clumps remained white before application and after application more clumps turned white. Markedly less bubbling from the algae. The Vallisneria now has taken noticeable damage, and some snails have died. No losses or signs of distress among the fish or shrimp. Day 6 & 7: most algae in the aquarium lighter in color, no bubbling at all from the algae upon dosing peroxide. I here stopped adding peroxide, and after about one week algae and plants had recovered.

It appears Cladophora are more resistant than red algae (see below), or possibly the concentration of peroxide was just too low. Some snails died, as did some of my Vallisneria, but none of my fish or shrimp. An interesting thing is that the algae took damage in direct proportion to how much light they received - the algae directly under the lights were the first to bleach, the algae in the shade seem unaffected. Also that it bubbled less every day was interesting - if anyone knows why this was, and why more light = more damage, please mail me.

Horsehair alga

This moss-green, irregularly branching alga in my aquarium grows exclusively inside the Vallisneria stands. I get the impression it does not really like bright light, and it is not very fast growing. If not removed it forms dense, almost spherical, clumps which eventually merge to form a kind of moss-like 'ground cover' under the Vallisneria canopy. It is not attached, and very easy to remove. Out of water the texture is quite rough, sufficiently so that the clumps retain their shape in air. It has a quite distinctive smell, which can actually be felt in the room.

I rather like this alga. It covers the bottom of the tank in a thick "moss" cover, and is easy to remove.

Initially I thought these were older branches of the "bushy" Cladophora species above, but I got suspicious because each filament is much coarser and less branching, and under the microscope it was evident it's a different species - my working name for it is 'wire alga'. It's got most of the characteristics of a Cladophora (see "bushy" alga above), but is not attached to the substratum, has thicker filaments, and seems to grow by throwing out looong (several cm) syncytial filaments which later form cell walls. Also it apparently has a kind of 'bark' - it's hard to explain, look at the pictures. Probably it is either a Pithophora which is not in reproductive phase, or a second species of Cladophora.

What eats it: The only animals I've seen which really are efficient controls of this alga are Neritina natalensis snails - they literally clear paths through it. Also the Amano shrimp keep picking at this alga, and I think their pruning is the reason it tends to form neat, spherical, clumps.

Common name: If it's a Pithophora, there is a common name: horsehair alga. If so a quite fitting name, given the coarseness and that older branches tend to turn black (due to iron deposits?).

Trivia: The diatom Rhoicosphenia curvata, found growing on this alga, is normally an epiphyte on Cladophora.

I noticed under the microscope that this alga was teeming with protozoans - mainly diatoms, ciliates and rotifers - and may be a useful alternative to java moss in brackish water breeding tanks.

The next alga is, as far as I understand, typical 'fur-' or 'fuzz-alga', the most ubiquitous alga in aquaria: an unbranched, soft, flowing, alga, firmly attached to and forming dense stands on e.g. glass, leaves, and driftwood. Size: up to at least 5 cm. This alga was collected from a freshly (less than a month) set up breeding tank - it is seemingly completely absent in my larger aquarium, possibly an indication it does not like hard water and/or high pH.

I believe this is Oedogonium due to: the expanded primary cells at the base of each strand, resulting from the settling of zoospores; the 'empty' cells from which zoospores have been released; the over-all smaller size of cells; and I can make out the telltale 'apical collar' between at least some cells (e.g. in Image 9 below), although they're not as conspicuous as in the pictures of Oedogonium on the net. Compare to the (rather better) images found here and here.

What eats it: Pretty much everything. Snails, amano-shrimp, and algae-eating fish seems to eat it, at least while it's not too long, and the constant "pruning" by these algae eaters may lead to the formation of short, dense, and not unattractive "lawns".

This is a weird one. It turned up in one big, single, clump, almost over night after I lowered salinity and added phosphate to the rift aquarium. The clump was soft, and not attached. I first thought it was the "bushy" Cladophora, but under the microscope it was evident it was not. I do not know what this alga is - it is reminiscent of Oedogonium. If so either a different species than the one above, or the different environment has changed the appearance of the alga quite a lot. Each individual strand in the clump is, at a guesstimate, 12 cm.

There were numerous bdelloid rotifers and a considerable number of juvenile amphipods in the clump. Also a number of young malaysian tower snails (Melanoides sp.).

This probably is the dreaded Staghorn alga, at least it looks much like the images of Staghorn at The Planted Tank, and it's been ID'd as staghorn by one of the moderators there. I'm also fairly confident that this is a red alga (Rhodophyta) of the genus Compsopogon. It is up to 4 cm long, and exploded into action, almost replacing the Cladophora species detailed above, after I added house plant fertilizer to the tank in an attempt to save my dying Vallisneria. More than likely it was the ammonium spike from the fertilizer which triggered it. The color is a sickly pale purplish gray, and it grows firmly attached along the edges of Vallisneria leaves, in medium light (not right under the metal halides, and not in the shade). There were numerous protozoans and rotifers among the filaments of this alga.

Fighting it: Siamese algae eaters (Crossocheilus siamensis), manual pruning, and gradually dropping nitrate levels eventually broke the back of this infestation. There is an interesting account on the net of how this alga can be killed with hydrogen peroxide. A poster at zoopet (swedish link here) reports having successfully used peroxide at a concentration of 33 ppm (300 ml of 3% peroxide to 300 liters of water) against this alga, a concentration which however also caused some damage to the plants of the aquarium.

Prior to this algae almost taking over the tank, I'd had small amounts of a small red alga growing along the edges of the Vallisneria leaves - typical "black beard algae", BBA. As red algae have haploid and diploid generations, which may look different, I speculated that the staghorn and the BBA might be different generations of the same alga. However, the people at the ALGAE-L mailing list found that very unlikely, instead they thought that there were probably two species of red algae involved. Quoting Orlando Necchi Jr.: "The first is probably the so-called 'Chantransia' stage (sporophyte) of an alga of the order Batrachospermales. It's very similar in morphology to the genus Audouinella, which can also be found in aquaria. An easy way to differentiate them is based on the color: the Audouinella species are reddish (any grade of red), whereas the 'Chantransia' stages are generally blue-greenish (or even dark brown or blackish). The typical color is the one shown in the figures of the site you mentioned. Compsopogon, the second alga, is most probably to reproduce only by asexual monospores."

Cyanobacterium 1

Below are images of a cyanobacterium which has manifested itself in my aquarium. It was for a long time growing in the sand close to Vallisneria roots (presumably it cooperates in some way with the Vallisneria) until I added house-plant fertilizer. After that it also spread up on the surface of the sediment and onto plants. Note the exceedingly small size and elongate shape of the cells - even at 400x, where a single Cladophora cell fills the screen, the cells of this cyanobacterium are just barely visible. The cyanobacteria filaments were constantly moving, flexing back and forth, making them rather hard to photograph.

What eats it: There were numerous microscopic nematode worms living in/among this cyanobacterium, and presumably feeding on it. Otherwise I've never seen anything eat it, although I guess something must be.

Other means of fighting it: Out of curiosity, I tested Aqua Furan, a medication containing the broad-spectrum antibiotic Nifurpirinol, active against both gram+ and gram- bacteria, and as expected it killed all exposed growth of this cyanobacterium. It is still present 1 cm or deeper in the sand, where it was apparently shielded from the antibiotic. Presumably any medication effective against gram-negative bacteria would have effect.

Equipment used: Nikon Coolpix 4500 digital camera - the concentric rings visible in some photos are due to imperfections in the camera lens. Zeiss-Jena Laboval 4 microscope. Camera/microscope interface from Brunel. Most pictures have had levels adjusted, and occasionally also been cropped and noise reduced, in Photoshop.

Legal stuff: All pictures in the algae gallery (and ONLY the algae gallery!) are public domain - you may use or modify them freely, for any purpose. I don't mind. Knock yourself out. All photos have been reduced to 1/4 original size, to avoid completely stalling people with slow connections, but if you want to have the full version of any image, just mail me.

So everything on this page is free. But please don't steal any of my other photos on my other pages without asking.

Disclaimer: I take no responsibility for the accuracy of the information presented here. I've done my best, but I'm no expert. If you find any errors, mail me about it.