FAQs on Freshwater Algae Identification Related Articles: Freshwater Algae & Control, Algae Eaters, Otocinclus, Loricariids, Siamese Algae Eaters/Crossocheilus,  Related FAQs: Freshwater Algae 1, FW Blue-Green Algae, FW Algicides, Algae Eaters, Aquarium Maintenance, Freshwater Aquarium Water Quality, Treating Tap Water for Aquarium Use, pH, Alkalinity, Acidity, Freshwater Algae Control, Algae Control, Foods, Feeding, Aquatic Nutrition, Disease,

Coralline algae growing in freshwater tank???  12/3/08 Hi all, <Robb> I have enjoyed reading through all the Q&As on your site. There is so much useful information. Thank you for the work you do. <Am very glad we can share> I have kind of a unique situation that I am unable to find much information about on the Web. Getting right to the question: Is it possible this is coralline algae growing in my freshwater tank? <Mmm, yes... but could be a few other possibilities...> I have attached a photo of the questionable specimen. This purplish colored growth is hard and scaly to the touch. It flakes off if I scrape it with my nail. So far, it is only growing on the rubbery parts of my faux saltwater decor. I have not seen any evidence of it growing on my rock yet. If this is coralline algae, how could it have gotten into my FW tank? <The spores... for algae... can be air-borne, come in through the tap/source water, in foods, decor, with the water with introduced livestock...> How is it surviving, growing, and spreading? <Conditions allow it> And most importantly, if it is coralline, how do I continue this growth? <Preserve those conditions, limit the introduction of predators and competitors> Tank specs and info: I have a 30g freshwater African Cichlid tank that I decorated to look like a saltwater tank. It has 4-5" of aragonite crushed coral substrate. Texas Holey Rock. It is filtered by an Eheim Pro II canister filter and an internal 24 watt UV filter. My lighting consists of six 6-bulb SuperBright White LED puck lights that I bought from Home Depot (provides that shimmer effect) <Neat!> and a 96 watt PC dual-actinic bulb (I also have a 50/50 bulb on hand). All decor in my tank (other than the TX Holey Rock) is faux marine decorations. I perform a 5g water change each week. I prepare my WC water a day prior to the WC. In a 5g bucket I add tap water, ~5ml water conditioner, 1 Tbsp Magnesium Sulfate, 1 tsp Sodium Bicarbonate, and 1 tsp Instant Ocean salt mix. The water sits in the bucket for at least 24 hours with a water pump providing circulation, air pump oxygenating the water, and a heater to keep the water at ~79 degrees. <Sounds/reads very good indeed> Water parameters as tested on 11/27/2008 @ 8:30 am Temp: 81.9 F PH: 8.2 Ammonia: 0 ppm Nitrites: 0 ppm Nitrates: 10-20 ppm Phosphate: 0 ppm KH: 8 degrees or 143 ppm GH: Either off the charts or test is expired (over 90 drops into test solution and no change in color) I have no tests for specific gravity, calcium, magnesium, or any of those other saltwater parameters. Livestock includes (2) Tretocephalus Cichlids, (2) Electric Yellow Labs, and a Pleco. All fish appear very healthy and active. Thank you very much for any insight you could provide! -Robb W. <I would enjoy this material... and take a look through a microscope at a bit of it if/when you can... the general structure of the cells, any inclusions can give ready clues as to the general Division or Phylum of the life here. Thank you for sharing. Bob Fenner>

Strange algae? 9/12/08 Good afternoon, I have been looking for an explanation and I haven't been so successful identifying this "algae". I have a moderately planted tank and a few of my plants, an Amazon sword and an Anubias most notably, have developed what I can only describe as a black rusty look on some of the leaves. It isn't a hair algae or what I have seen of black algae on the internet, in fact there is no actual stubble, hair, moss or anything...it looks more like mold on a piece of bread, but blackish. Any ideas what this could be and how to get rid of it? tank is a 20 gallon long with 40 watts lighting. ph about 7.8 set up for a long long time <Greetings. Anubias are adapted to living in shady environments, and so unlike plants from bright light environments, they don't have adaptations that help them keep free of algae. Because their leaves are slow-growing, if you put them in a bright spot, they do tend to get covered with algae. In small amounts this doesn't do much harm, but over the long term can end up smothering the leaf, perhaps speeding up decay. In any case, there's two steps to keeping Anubias algae-free. The first is to put the plant under some shade. Floating plants are great for this, otherwise just use something fast-growing that will cut out some, though not all, of the light. Secondly, use Nerite snails or some other gentle grazer to remove algae from the leaves. Plecs and bristlenose Plecs don't work -- they tend to damage the leaves -- so if you opt for a fish, choose a gentle species like Garra flavatra or Crossocheilus siamensis. Amazon Swords should be largely algae-free if they're happy, though hair algae along the edges of the leaves can be a problem. Again, Nerite snails or some other gentle algae-eater can help, but otherwise simply pulling away grossly infected leaves is usually the quickest fix. Do bear in mind Amazon Swords won't be happy if the light intensity isn't strong enough for them. You're looking at 2+ watts per gallon for most Echinodorus, coupled with a rich substrate (not plain gravel!) and appropriate water chemistry and temperature. Cheers, Neale.>

Re: strange algae? 9/13/08 Hi, <Hello again,> I have about 2 watts per gallon. <When you say "about" what do you mean?> I was just wondering if this is some kind of maintenance issue that I am overlooking. I do a 20% water change weekly, I have sand and gravel mixed, so I usually do an off the top vacuuming, as far as filters... <Sand and gravel by themselves aren't going to feed your plants. Imagine sticking a pot plant or garden plant in sand or gravel. Would you expect it to live for long? Obviously not. While fish wastes to indeed provide some nutrients, particularly nitrate and phosphate, iron and other minerals are lacking. The ideal approach is to put some soil in the substrate, usually by mixing with gravel first to stabilise it, then sealing it in with a "gravel tidy" (really just a mesh) and then covering that with some clean gravel or sand. That's perhaps not an option here, so instead you'll need to use fertiliser pellets and insert them close to the roots of the Amazon Sword. One pellet a month should do the trick nicely. You'll notice that the leaves on your plant are quite pale yellow-green, and that's commonly a sign a plant is "starved" of iron.> I usually rinse the pad if it is overflowing back over the intake or replace it if it seems extremely loaded and clogged. I use a penguin 150 and a whisper 10 on a 20 gallon long (30") aquarium. I use flourish occasionally, but not usually weekly. Tank is lightly stocked with a couple of small platies and a bumblebee catfish. Lights are on 12 hours a day. <You could try switching to 5-6 hours on, 2 hours off, then another 5-6 hours on. This "siesta system" for reasons not entirely clear does seem to stress algae without harming plants.> This particular algae is also on some of the rocks and gravel. The algae on the sword plant is on the older leaves, not so much on the newer ones. <It's common for algae to get to old leaves before new ones, for reasons to do with how plants naturally keep themselves in algae-free in the wild. If algae is everywhere in the tank, do review the causes of algae, particularly direct sunlight and excessive nitrate and phosphate in the water. I'd recommend some Nerite snails for basic algae-removal, and perhaps some shrimps, though I'd be concerned the Bumblebee Cats would eat them.> Do you think a filter intake tube and filter box cleaning/and a thorough gravel cleaning might be in order...or possibly more flourish and smaller more frequent water changes could help get this under control... <The filter itself shouldn't be a major factor, though if the filter is clogged then water flow will drop, and that does favour Blue-green Algae especially.> Do you know what type of algae it is?? Sorry about the quality of the picture. <Different conditions favour different algae. Green Algae like bright strong light and clear water. It's almost never a pest because most fish eat the stuff readily, and it isn't the alga you're dealing with here. Blue-green Algae looks like red, black, or blue-green slime, and usually occurs where the water is polluted (i.e., nitrate-rich) and/or water flow is weak and/or the tank is getting direct sunlight. Red Algae, despite the name, is brown to blue-black in colour (or at least the freshwater varieties are). It does well in polluted tanks with poor water movement; it doesn't seem to need bright light. It tends to look like threads or fuzz and grows on solid objects and very often as a fringe around the edges of leaves. I suspect that's the algae you're dealing with. Finally, there's Diatoms (or Golden Algae) which form the greasy slime you get on the inside of the glass walls of the tank. Characteristic of dimly-lit and/or immature tanks. Usually settles down by itself, so rarely becomes a major problem. Cheers, Neale.>

Black coloured algae in tank -05/15/08
Hi I have a 3Ft tank with African Cichlids in it. My water has always looked great... last week my Electric yellow died for no apparent reason and the same day I noticed lots of fry in the tank. Did she die during childbirth?
<Unlikely. Perhaps she starved to death, since they can't eat while mouthbrooding, which is why you *must* isolate the females for several weeks (ideally months) to "fatten up" before placing them in a tank with males of their species. If she died, the fry could easily have swum out.>
I removed the fry and then all of a sudden this creamy/brown slimy stuff appeared everywhere. I did a water change, taking out almost half the water, the tank seemed fine for a few days and then all of a sudden the tank is now very cloudy with black soot looking algae? all over the rocks, gravel and plants (all artificial).
<Doesn't ring any bells I'm afraid. Blue-green algae is notorious for suddenly appearing, but is very distinctive in appearance. The usual "black" algae is hair algae, actually a dark reddish-green, but again, it is very distinctive.>
I cant seem to find any info when I Google images for black looking algae, nothing looks like the stuff in my tank. yesterday I vacuumed the tank, took out and cleaned the plants and rocks and its all back again just as bad as yesterday.
<A photo would help. But by default, here are the things you do: First check water parameters, at minimum nitrite and pH. Secondly clean the filter, obviously taking care not to harm the bacteria but otherwise rinse out any detritus. Finally, do a big (75%+) water change and give the gravel a deep stir and siphon while taking out the water.>
Thanks in advance for your help.
<Cheers, Neale.>

Red-orange residue in freshwater Cichlid tank... Likely BGA...  2/18/08 Hi!! <Hello Christina> I have a 75 gallon tank that has been set up since Xmas of 2007. It cycled very well and houses African Cichlids of various types. Everyone is happy and doing very well...I have two female holding eggs and possibly one more, not sure yet. About two weeks after setting the tank up I notice a red-orange slime that started to cover everything in the tank. <Yuck!> It is very obviously coming from the surface as it does not cover surfaces under plants or other decorations. I have had no Cichlids die though I have twice put in an algae eater (Plecostomus) and they both died within two days. <Yikes> Recently I clean all decorations, did a 50% water change and within one week the slime was back. <Good name for it... is likely to some large extent a Blue-Green Algae... aka Cyanobacteria... many can be quite toxic to ingest> The city says it's the water system we have that removes all chlorine, <Mmm, the system you have at home? As in some gear to treat the potable source> but the water system people tells us that it's the city water and is a result of oxidized iron settling in the tank. <Mmm, doubtful... not this amount... not to where you can actually see it accumulate> I am at a loss and very disappointed because the tank looks so bad. At least my little guys are okay right now. Any insight would be wonderful. Thank you so much for you time, Christine <Mmm, there are a few approaches to limiting, controlling BGA... More circulation, chemical filtration, sequestering microbiologically, competition with other photosynthetic life, nutrient export... Please read here: http://wetwebmedia.com/FWSubWebIndex/fwbgafaqs.htm and the linked files above. Bob Fenner> Re: Orange slime, FW algae ID, contr. f's    2/19/08 Thanks so much Bob...I will read up on that link right now. I forgot to mention that we also have the red color in our showers and toilets. This is why I think it's the water and not something in the tank. <Mmm, maybe, but just a small possibility these are the same... the shower is likely a ferrous stain, but the pix you sent show an algal sort of growth...> Our water system guy did say that coquino has a lot of iron in it, but I didn't think it would be so high as to leach in and settle so quickly. <Mmm, no... if this "high", the life would be gone entirely here. The iron however is likely aiding the BGA... > Our system is a softener with a carbon filter. I attached a couple pictures and now that I'm looking at in in the pictures it seems more orange-brown. In the first picture you can see how it settles as there is a distinct line where there is no slime. Can algae grow so quickly? <Oh yes... some forms/types can double their biomass every few hours...> Two weeks ago tomorrow this tank was very clean of this slime. Thanks again for all you help Christine PS...That is my female Yellow Lab that has been holding eggs since last Tuesday...any idea when they might hatch??? <Should be within four days or so at temp.s of the higher 70's, low 80's F.> Thanks again!!! <Do read re means of limiting this algal growth... Bob Fenner>

Algae or what? FW   11/1/07
Hi Crew,
Recently ( 3 month ago) I setup planted 20 gallon hexagon tank:
fish= 6 harlequin Rasboras and 3 gold rams
plants= water sprite, Amazon swords, java moss and java fern.
Water parameters: pH= 6.7, NH3= 0 ppm, NO2= 0 ppm, NO3= 5 ppm
Lighting= 40 Watts, 12 hrs per day
<All seems fine.>
I do not have any algae on the glass at all, but I see long gray hair on the driftwood. What is that? Is it dangerous for fish?
<Ah, no, this isn't algae, but is likely fungal or bacterial in nature. It's common on bogwood (or any other kind of wood) that hasn't been "cured" properly. It indicates that the wood still contains sufficient organic material for bacteria or fungi to feed on. It is basically harmless, though perhaps unsightly. You can wash it off if you want. Some fish will eat this "mould", such as Plecos, and snails and shrimps may well peck at it too.>
Thank you for your help
Mark
<Cheers, Neale>

Algae issue - short black fur 10/3/07
Hi WWM crew,
I have hunted everywhere for a solution to my algae issue with no luck.
It looks like short dark brown/black fur. It's about 6-7mm (0.3 inches) long and really thick (just like fur) and it's covering all of my rocks and even most of the plants. I have been looking for solutions such as creatures to eat the algae, but have had no luck. I have other tanks in more daylight and they don't have this algae problem so it's not a question of light. The tank with the problem is a 200L community freshwater with alkaline pH, 26 degrees Celsius, low population (2 small calvus, 2 Bristlenose cats, 5 small to medium rainbows, 1 small dickfeldi, 1 medium butterfly, 1 medium Kribensis). The tank is mostly landscaped with rocks, but there are some hardy plants (still getting
shredded by the fish!) and 1 long, thin piece of driftwood.
Hope you can help because my once beautiful tank is looking like some weird furry alien landscape - very bleak and dull!!
Thanks!!
Lachlan
<Despite the blue-black colour, this short furry algae is a type of red algae. Nothing really likes to eats it. Almost certainly the problem is lack of natural plants while having relatively bright lighting. For example, you usually see this sort of algae in either unplanted tanks or tanks with slow growing plants like Anubias and Java fern. So, there are two options. The first is to add fast growing plants like Hygrophila, Cabomba, or even floating plants. Through allelopathy, these plants will prevent algae of all types growing. You may need to increase the lighting in the tank for this to work though -- paradoxically, algae is more of a problem in poorly lit tanks than strongly lit ones! The alternative is to accept it as part of the environment. The fish certainly won't care, and especially at breeding time, this hair algae forms a home for the micro-organisms baby fish like to eat. About the only fish I know of that eats this type of algae is Jordanella floridae (the Florida Flagfish) though only when hungry. How effective they will be against an established population I can't say, but since they're nice fish in their own right, definitely worth a shot. Cheers, Neale>