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Algae Eating Cyprinids from Thailand and Neighboring Areas
(c) Copyright 1994 N. Frank and L. Sarakontu
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Ed: There is a much more accurate and better HTML translation on theAGAVersion of this article, so you may wish to read it there.Unique to this site,here are some photos oftwo small SAE's inmy tank... andone big one amongst some rummynose tetras. -EO]
This article talks about five fishes from Thailand andneighboring areas, including the elusive Siamese Algae Eater(Crossocheilus siamensis) which is the only known fish toeffectively eat red (beard/brush) algae. The other four fishesare (1) a very similar fish which we call the "false siamensis,"(2) a more colorful relative - the Flying Fox (Epalzeorhynchuskalopterus), (3) anotherCrossocheilus species and (4) theChinese algae eater. To the casual observer, all fish may lookthe same at first. Even some reputable aquarium texts haveconfused the real and false siamensis. A summary table isincluded at the end to compare the distinguishing features among theseinteresting fishes.
This slender algae eating barb is the only known fish that eatsred algae. It comes from the flowing waters of Thailand and theMalay peninsula. It was first brought to Europe in 1962, butbecame popular in the 1970's when its ability to eat red algaewas noticed. The fish is also known as Siamese Flying Fox, andSiamese Fox. It previous scientific name wasEpalzeorhynchussiamensis. To those interested in the fine, but admittedly boringdetails of taxonomy, the genusCrossocheilus differs fromEpalzeorhynchus by rhynal lobes (nasal lobes).
Description
It is a slender, grayish-brown fish with a distinctive blackhorizontal stripe. Maximum length is 15 cm (6") and might beobtained in two years, if the conditions are optimal. NormallyThey grow slower and don't always reach that size in captivity.They can live over 10 years. All the fins are transparent orslightly milky without any yellow or reddish sheen. The blackband goes from nose to the fork of the tail and its edges arezig-zagged. When a fish is stressed or fighting the black colorfades significantly. Underparts are silvery white and there is nolight stripe over the black, but the whole upper body is brownishand every scale has a dark edge, which make the top lookreticular. Some dark scale edges might be seen under the blackstripe. It has a pair of thin, forward-pointing barbels but theymight be pressed against the cheeks when fish is swimming orresting. The long black stripe is also easy to see in youngfishes, but the scale edge pattern and zig-zag edges are notclearly visible until the fish reaches the length of 5-7 cm(2-3"); the ones that are normally seen in European shops areabout 3-5 cm (1-2") long. Adult females are often slightlyfatter than males, no other sexual differences are known.Behavior
It is an active and fast swimmer, which thrives best in schoolsbut can also be kept alone or in pairs. It is a strong jumper andshould not be kept in uncovered tank, because it will eventuallyjump. Siamese Algae Eaters often chase one another but theynever get hurt in these fights.C. siamensis has a peculiar resting position: it doesn't lie flaton its belly but keeps its body propped up with its tail, pelvicand pectoral fins. Young fish sometimes rest on broad leaves,adult specimens prefer resting on bottom or dense, low plantslikeCryptocorynes. The swim bladder is not very developed, sothe fish can't stay in midwater but it must be in constant motionor it sinks.
Needs
Siamese Algae Eater is not very demanding. Suitable temperatureis 24-26 C (75-79F). They can tolerate pH from 5.5 to 8.0, but6.5-7.0 is ideal. Hardness should be less than 20 dH. Water should be clean andoxygenated, because they come from bright and fast-flowingstreams. They eat algae, including red algae and all kind of liveand prepared foods. It is very rare that they harm plants intheir tank if they are given enough green food. They also eatalgae when they are mature, but seem to prefer flake food.Liisa's fish eat Duckweed (Lemna minor) but have never touchedany other plants. They haven't yet been bred in captivity, so allthe specimens are caught from nature. It appears that the fishare seasonal and are not always available in the shops. Minimumtank size for a pair of adult Siamese Algae Eaters is 100 liters(25 gallons). The aquarium should be long and have lots of livingplants.
Compatibility
As they are not aggressive, they can be kept in any communitytank big enough. Their active behavior might stress somesensitive species like dwarf cichlids and prevent them fromspawning. They should not be kept with Red-tailed Sharks(Epalzeorhynchus bicolor) unless the aquarium is large and wellplanted, because that species is very aggressive towards all itsrelatives. This algae eating barb strongly resembles the Siamese AlgaeEater. It comes from the same region and at least young specimenscan school together. These fish are often mistaken for realSiamese Algae Eater and in Finland it is common to see somespecimens among a tankful of Siamese Algae Eaters. It seems thatthe real Siamese Algae Eater is a rarity in US, and the "falsesiamensis" is normally sold as Siamese Algae Eater. Moreconfusing is that many respected Aquarium books (e.g. BaenschAtlas, Volume 1, english edition) present this fish as theSiamese Algae Eater (Crossocheilus siamensis).There is still some uncertainty regarding the true identity ofthis fish. Markku Varjo states that it is the Siamese StoneLapping Fish (Garra taeniata Smith 1931), but other veryknowledgeable aquarists (including Heiko Bleher and FumitoshiMori) believe it is some species ofEpalzeorhynchus. Moreinformation from Heiko will be forthcoming from the authors.
Description
At first sight this fish is just like the Siamese Algae Eater,but they are easy to tell apart when you know what to look. Theblack horizontal band does not go to the fork of the tail butstops at the base of the tail and its edges are rather smooth.When the fish is frightened the black stripe fades to light grey. All fins except pectoral are yellowish and there are darkmarkings on the dorsal fin. The rays near the base of the dorsalfin are black and there is another dark band in the upper part ofdorsal. There is a distinctive narrow light stripe over the blackhorizontal band and the dorsal region is solid grayish brownwithout dark scale edges. The top area is also slightly darkerthan Siamese Algae Eater. Sometimes bright red or pink is seenaround the mouth but it might disappear if the fish is stressed.It has two pairs of barbels (unlike the Siamese Algae Eater). Maximumlength is reported to be 15 cm (6"). No sexual differences areknown, but the amount of red might depend on the sex of the fish. In the orient, these fish are called "colorful flying fox." Ironically,Crossocheilus siamensis is called "the one likeflying fox."Behavior
Adult specimens are aggressive towards each other, otherwise likeSiamese Algae Eater.Needs
"False siamensis" is more demanding on water quality than SiameseAlgae Eater. It needs very clear and oxygenated water, idealtemperature is 24-26 C (75-79F) and the pH shouldn't get muchunder 7. They eat some algae, but in nature they probably seeksmall animals from algae growths. In aquarium they eat all kindsof live and artificial foods. They have not been bred incaptivity. Minimum tank size for it is 80 liters (20 gallons).Compatibility
Can be kept in any community tank. Adult specimens often getaggressive toward each other, so there shouldn't be more than one"false siamensis" in a tank. They might also harass related species and other small bottom-dwellers like loaches, if the tankis not big enough. The Flying Fox is the most colorful of this fish group. For thisreason, it has gained popularity in the U.S. overCrossocheilussiamensis and "false siamensis". It comes from the flowing watersof Thailand, Sumatra and Borneo. Wholesalers sometimes deliverthis species as Siamese Algae Eater in Finland. This fish is alsoknown as Trunk Barb.Description
Body and fin shape like two previous species. Thin specimens areoften pictured in the aquarium literature. The overall color iswarmer brown or even goldish and the black horizontal stripe goesfrom nose to the fork of the tail like on Siamese Algae Eater,but the part going through the tail fin in darker and broader.There is a narrow golden stripe over the black. Dorsal, anal and pelvic fins have indistinctive dark bands and bright white tips.It has 2 pairs of barbels. Maximum length is reported to be 15 cm(6"). No sexual differences are known.Behavior
Same as previous species. Adult specimen is territorial andaggressive towards its own kind.Needs
Ideal pH is near 7, temperature 24-26C (75-79F). It eats allkinds of live, prepared and plant foods. It has not been bred incaptivity. Minimum tank size 80 liters (20 gallons).Compatibility
Flying Fox can be kept in a community tank, but it might chaseother fish viciously from its territory. There shouldn't be morethan one adult Flying Fox in a tank.Crossocheilus oblongus (Cuvier and Valenciennes, 1842)
This is a close relative to Siamese Algae Eater, and it ispossible that specimens of this fish are sometimes found inschools of Siamese Algae Eater or "false siamensis".Description
Body shape and color are basically same as Siamese Algae Eaterand "false siamensis". All the fins are transparent and the blackhorizontal stripe does not extend to the tail fin. The stripehas smooth edges and the back is solid, not reticulated like onSiamese Algae Eater. It has two pairs of barbels like Flying Fox.Maximum length is 10 cm (4").Behavior, needs and compatibility
Probably same as previous three species. This Algae Eater belongs to family Gyrinocheilidae, although itresembles both loaches and Algae Eating barbs. Its English nameisn't very accurate, because it comes from Northern India andThailand, not China. It is also called the Indian Algae Eater. There are still some unclear points in the systematicclassification of this genus and it is possible that the speciesmost often imported isn'tG. aymonieri butG. kaznakovi. Thereare also two other species (G. pustulosus andG. pennocki).Description
Chinese Algae Eater is a bottom-dweller. The most prominentfeature is a big suckermouth, which it uses for scraping algaeand clinging to objects. There is a special opening on the upperpart of the gill cover for the water intake so the fish canbreath without using its mouth. This same feature is seen onSuckermouth Catfishes. The fish is light brown and there is adark grey or brown horizontal pattern on its side, which can beeither a zig-zag edged solid stripe or a row of separate spotsor anything between these two. Young specimens are more colorful.There are some dark patches at the back and small brown spots atthe tail. All the other fins are transparent or slightlybrownish. Maximum length is 27 cm (11") but normally it doesn'texceed 15 cm (6") in an aquarium. Females are larger and fuller,adult males might show spawning tubercles on the head.Behavior
It moves along all the surfaces of the tank scraping green algaewith its suckermouth. Older specimens prefer artificial foods andare rather aggressive.Needs
Chinese Algae Eater is not very demanding on water conditions: pH may vary from 6.0 to 7.5 and the temperature from 22C (72F) to28C (82F). Water should be well oxygenated, as it comes fromstreams. It eats all kinds of foods, but must get enough algaeor plant food. It is reported that it will stop eating algae ifthe temperature drops below 69 degrees F (20 deg. C). It has notbeen bred in captivity. Minimum tank size 100 liters (25gallons).Compatibility
Young Chinese Algae Eaters can be kept in community, but adultspecimens can be aggressive to other fish. They most often attackslow-swimming, flat-bodied fish and shouldn't be kept with them.Distinguishing features
---------------------------------------------------------------- C.siamensis "False s." E.kalopterus C.oblongus G.aymonieri-----------------------------------------------------------------Horizontal stripe: - edge: zig-zag smooth smooth smooth uneven - extend to tail: yes no yes no - lt.stripe above: (sometimes) yes yes ?-----------------------------------------------------------------Dorsal region: reticulated solid ? (black edged grayish scales) brown-----------------------------------------------------------------Fins - dorsal: transparent dark dark bands trans- trans- lower rays & white parent parent & yellowish tips - anal: " yellowish " " - pelvic: " yellowish " " -----------------------------------------------------------------Mouth: small,non- clinging clinging sucker suckermouth mouth (maybe with red/pink)-----------------------------------------------------------------Barbels: 1 pair 2 pairs 2 pairs 2 pairs none-----------------------------------------------------------------
References
Varjo, M. 1989: Akvaariomaailma. - WSOY. Porvoo. Varjo, M. 1983: Levabarbi vai mika? - Akvaariolehti 3/83:16-19.
Petrovicky, I. 1988: Aquarium Fish of the World. - Arch CapePress, New York.
Mills, D. et al 1988: Tropical Aquarium Fishes. - Tetra Press,NJ.
Axelrod, H. 1989: Atlas of Tropical Freshwater Aquarium Fishes. -TFH, NJ
Riehl, R. and Baensch, H.A. 1989: Aquarium Atlas (Volume 1), - MERGUS, Germany.
Smith, H.M. 1945: The Fresh-water Fishes of Siam, or Thailand.Bulletin 188 - Smithsonian Institute, Washington D.C.
Liisa Sarakontu
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