|
|||||
|
|
|||||
The Genus Oryzias
For years I wished to keep some Oryzias in my tanks, but despite the fact that at least the "javanicus" occurred now and then in Germany, no specimens were apparently imported into Denmark. I had to wait until one day Peter Trang informed me that he would like to mail me some eggs from the Golden Oryzias (that is O. latipes, native to Japan. Golden means that Peter had the "var. auratus", an orange-red variety raised by the Japanese). Shortly after Thung Kim Tek offered me to send eggs from the O. javanicus, native to Java and other islands of Indonesia. Tek also sent eggs from a minute "Oryzias" which may be a new one. So within a few months I got 2-3 different species of the genus I was longing for. Perhaps even more species will come during 1960 in order to make crossings possible.
The name of the genus
It all began with McClelland who in 1839 described a new genus, Aplocheilus and unfortunately (for us) placed two different species in it. One was A. chrysostigmus, the other was A. melastigmus (Now Oryzias melastigma, native to India and Burma), but he forgot to tell which of the two species should be the type. A. chrysostigmus later on was found to be identical with Esox panchax (now Aplocheilus panchax, also a killie of Asia, but "panchax-like"). McClelland's two species of Aplocheilus had to be placed in two different genera. In 1846 Cuvier &
amp;
Valenciennes described a new Asian genus of killies, the Panchax with P. buchanani (now Aplocheilus panchax) as type. In 1906 Jordan &
amp;
Snyder established the genus Oryzias for the "latipes" species only (?).
Until recent times the fish now considered to be Oryzias have been called Aplocheilus, whereas the ones now considered as Aplocheilus were mostly called Panchax. Inbetween the generic name of Haplochilus was commonly used for both groups of killies also up to recent times. Myers in his great survey on killies in 1924 (Copeia), 1931-33 (Copeia) considered Oryzias to be a synonym of Aplocheilus (our Oryzias) and the other Asian killies (lineatus etc.) to belong to Panchax. In 1931 he separated the Aplocheilus (Oryzias) in a particular tribus, named the Aplocheilini (later called Oryziastini) whereas the Panchax (Aplocheilus) were placed in the Rivulinii. In 1924 Ahl (Zoologischer Anzeiger) divided our present Oryzias into two genera (in accordance with Jordan & amp; Snyder) by the way that he placed "latipes" in Oryzias and "melastigma", "javanicus", "celebensis" and "timorensis" in Aplocheilus. The "panchax-like" species as "lineatus" etc. he placed in Panchax. In 1943 Nichols (The Freshwater Fishes of China) considered Oryzias as a subgenus within Aplocheilus ("latipes" and perhaps one more species? only). Since Stoye used Oryzias in 1947 (Aquarium Journal) for all the Asian species near "latipes", Aplocheilus fell out of use for these fishes. In 1955 Myers (Tropical Fish magazine, March issue) changed in some way his division of the fishes within Cyprinodontidae in the way that he changed most tribes into subfamilies and hereafter the genus Oryzias is the sole genus in the subfamily Oryziatinae.
Placement within killies
With the placement as the sole genus of a particular subfamily (formerly as a tribus or tribe) in Cyprinodontidae these poor fish certainly are rather isolated indeed. Their closest relatives possibly are the genera in the subfamily Procatopodinae (formerly the tribus Aplocheilichthyninii) that is to say the African Lampeyes (Oryzias might be called the Asian Lampeyes!). However, they are somewhat bigger than the best known African Lampeyes, the Micropanchax (also called Aplocheilichthys), the M. macrophthalmus, M. loati, M. pumilus etc. Oryzias reminds more of the little known species in Hypsopanchax and also of the Procatopus. But the eggs of Oryzias are not at all like those of Aplocheilichthys or Procatopus (I have only seen eggs from one Procatopus, on the contrary eggs from 5 species of Micropanchax). Interestingly enough the eggs of Oryzias remind one of the eggs from Nothobranchius and also of Cynopoecilus by having short and stiff "hairs" standing right out from the membrane. In Oryzias these stiff hairs no doubt are of importance in keeping a certain space between the many eggs in the cluster of eggs which is carried by the females.
Asia has also another "killie" (at least it has been placed in the order of Cyprinodontes or Microcyprini), the strange fish called Horaichthys setnia, a minute fish living in tidal brackish pools near Bombay in India. By some characteristicss this little fish seems to be related to Oryzias. Advanced aquarists should take the time to read Kulkarni's very interesting paper on this odd fish in "Records of the Indian Museum". Vol. XLII, 1940 (1941). Possibly we need a "killie friend" in Bombay!!
The species in Oryzias
I have been copying the original descriptions of very many killies during the recent years, but no doubt I will have to copy another 10-20% before I have all the important descriptions and articles. Therefore I am not sure if some species did not find their way into my collection of descriptions and among these fish some Oryzias might be missing. I found the following species to be described:
Aplocheilus cyanophthalmus (Blyth 1858) and Aplocheilus carnaticus (Jerdon 1849) are O. melastigma. A. argyrotaenia (Tirant 1883) might be an Oryzias also ("javanicus"?). Also I do not know if nr. 2, 5, 6-7, and 10 still are considered as "good species". Here is some "zoological data", L/H is "length divided by deepth of body, "s" for "standard length" (fish without caudal fin), "t" for "total length" (fish measured with caudal fin), "D" for "rays of dorsal fin", "A" for "rays of anal fin", "LI" for "scales in a longitudinal series". You will find no marked differences between the various species:
(this chart needs help with it's headings - RJS)
L/H D A LI t
O. curvinotus 3.4 s 6 25 ~35 25 mm?
O. javanicus 3.75 s 7 21-23 29-30 40 mm
O. latipes 3.5-3.9 t? 6 19-20 29 40 mm
O. luzonensis 4.0-4.3 t? 5-7 15-18 30-35 30 mm
O. marmoratus 3.5-4.2 t 8-10 21-24 29-36 46 mm
O. matanensis 3.2-4.4 t 7-9 21-24 40-47 53 mm
O. melastigma 3.8-4.0 s 6-7 20-24 27 50 mm
O. celebensis 3.7-4.4 t 7-10 17-22 30-32 50 mm
The various species are not very colorful. The body is somewhat transparent, the sides of the body give away a brilliant cast in a certain angle of light, the metallic colors being green-blue-violet. The pigmentation is weakly developed and most often it is found as a narrow blackish band along the sides from the roots of the pectorals and backwards till the root of the caudal where it may separate forming two branches running into the upper and lower lobe of the caudal fin. In some species there are also some dark spots on body or fins. Also the red-yellow colors are very weakly developed, at least in the "natural" species. Only in the golden form of "latipes" is red-orange is abundantly present.
Here is some particular data of the species:
O. celebensis: greenish gray to yellowish bluish metallic cast. A narrow longitudinal band from roots of pectorals to root of caudal dividing into two running into the caudal lobes. Big, mature males may have a narrow blackish stripe just above the root of anal fin. Males have prolonged anal rays and also its dorsal fin produced into a pointing tip.
O. curvinotus:?
O. javanicus: yellowish to faint greenish gray, blue metallic cast changes into violet. A dark stripe along the back. A very narrow black band along the sides and another just above the root of anal fin. Vertical fins are yellowish in male and in both sexes this fin may have a whitish blue border. Males have the biggest fins with the dorsal fin being pointed.
O. latipes: silvery, with bluish cast, greenish towards the back. Belly yellowish. Fins mostly colorless but often they are provided with fine dark spots or with an orange border. Sexual differences not very pronounced.
O. luzonensis: grayish, with a yellow sheen above and a silvery luster along the sides. Some specimens have dark spots scattered over the sides posteriorly, and on the caudal base, dorsal, anal, ventrals, and upper and lower portions of caudal are usually yellow or yellowish, but may be colorless. Sometimes there are one or two cross rows of black spots in the central part of the basal half of the caudal. Pectorals colorless. Preserved specimens also have a narrow blackish lateral line and a blackish line on the back, sometimes also a black line above the root of the anal fin. Fins usually colorless, but they might be more or less black!
O. marmoratus: preserved specimens are brownish to "flesh colored". The sides of the body are marbled with black spots. There are 9 (5-9) diffuse traces of cross bars (spots). Black stripe along the back composed of 3 lines.
O. matanensis: preserved specimens are "flash red". In the middle of the side there are some 6-11 dark spots forming "cross bars". Black line on the back and along the lateral line. Matured specimens also have dark fins.
O. melastigma: greenish gray. Greenish metallic cast. Several small or large dark spots on the sides of the body. A dark blue lateral band divides into two which run into the lobes of the caudal fin. Fins colorless or greenish or yellowish red. The border of the anal fin may be white in matured males. You see that the general pattern (not always present in the live fish) does not differ much within the whole genus.
Behavior in the aquarium
The species are known as rather lively fish which similar to "lampeyes" like to shoal with their own. They are quite harmless and most authors say that they even do not eat their eggs or the fry. They take live food as well as preserved food. Also species are not considered as feeble under the common conditions offered to them in the tanks of the orthodox aquarist. It has been the opinion of older authors that (at least the "javanicus") should be kept rather warm (above 25 C and up to 30 C), but recent authors claim that the "javanicus" does not need higher temperatures than most other aquarium fish.
Nieuwenhuizen kept specimens at 9 C without any harm and considered 18-24 C to be a practical temperature range. He warns against higher temperatures (above 26 C). He and other aquarists kept this species in rainwater and found no particular water type to be the best one.
Hoffmann (DATZ 1954) kept his "javanicus" at 23-25 C, but they did not suffer at 18 C. They did not like temperatures above 26 C. No response to different water types nor the lighting. This stock was not very willing to take dry food.
Birkholz (DATZ 1959) found that his stock did not like strong sunlight and that the species was rather shy in the community tank. He kept his stock at pH 7.7-8.3, temporary hardness 12.8-20.5 German degrees, total hardness 16.4-30 German degrees (but also eggs did not hatch after the normal period, see below).
Muller (AuT 1956) kept her stock in soft (2 German degrees) and slightly acidic water (pH 6.5) (eggs hatched within 10 days at 28 C).
The breeding of Oryzias
O. javanicus is the best known species. Stock was reimported by Werner, Munich in 1953 and this stock possibly still lives in Europe. It is characterized by a handsome whitish blue edge on the anal fin and (Foersch) small white spots on body sides and sometimes also on fins. Dr. Foersch, Hoffmann and Birkholz report on breeding in DATZ, Nieuwenhuizen and Muller in AuT.
The spawning act normally seems to take place in the night (Foersch and Nieuwenhuizen, possibly also Hoffmann). Birkholz reports that spawning took place between 6:30 and 7:00 in the morning. Foersch was the first to describe the spawning act in details: male chased the female for 2-5 minutes. The male then came at the side of the female which did not move. From the side he saw that the head of the male was little lower than that of the female. From above he saw the bodies forming a "Y" (as in Nothobranchius and Aphyosemion). Male now folds its anal fin around the bottom part of the female's belly. The fin completely enfolds the female's body and one can see the blue seam of the male's fin halfway up on the other side of the female's body. The couple slowly sinks. Eggs then are spawned and fertilized by the male in the "sack" formed by its large anal fin. The whole mating process takes about 20 seconds. Eggs then are hanging from the belly of the female on both sides. Female then carries around the eggs but in course of the day she deposits the eggs on plants or perlon. Nieuwenhuizen noticed that females in tanks with no plants but duckweeds deposited their eggs one by one on the tiny roots of the duckweed, whereas in tanks containing plants they normally deposited eggs in clusters containing each many eggs.
Eggs are small, about 1 mm in diameter. They are very sticky and adhere closely to each other and to plants. The slimy filaments are very elastic and it is very difficult to separate eggs in a cluster from each other. Eggs are hard-shelled and may be handled using your fingers. The spawning takes place every morning for up to two months, then pairs do not spawn for some days or weeks and after this resting period spawning starts again and goes on for another 2 months and so on through the whole year. The percentage of fertile eggs seems to be very high under all conditions. Eggs are not sensitive against light or infusoria. According to Nieuwenhiuzen the normal number of eggs is about 40 (20 on each side). Maximum being about 50 eggs. That means that the species under fine feeding conditions is very fertile indeed.
The various data from the reports show that the period from the spawning to the hatching varies greatly in this species. Foersch says 3-4 weeks at 25 C and 4-5 weeks at 23 C. However after a few days there were several dark spots visible in the eggs, and after 5 days the formation of the eyes became visible. Embryos turned around constantly within the eggs (no doubt these eggs had resting fry). Water conditions unknown. Muller, M. says about 10 days at 28 C (water soft and acidic). Birkholz says 40-45 days at 21-23 C (water very hard and alkaline). Hoffmann says about 14 days (data of water and temperature unknown). Sauer (according to Nieuwenhuizen) says that 2/3 of eggs needed 55 days at 22.5 C, the remaining eggs needed 8 weeks and they had to be forced out of their shells using the method where a breeder strongly shakes them in water. Nieuwenhuizen moved eggs to breeding containers as the females spawned them. Water hard (13 German degrees -not a word on pH or on temporary/total hardness!) at 25 C hatching came after 16-20 days. At 22 C they hatched after 4 weeks. At 18-19 C it took 7-8 weeks. At 28 C he was able to see the eyes of the fry after 4 days only! After 9 days (at that temperature) the fry were ready to hatch and on 10-11 days the fry came out. The fry then had large yolk sacks. After 24 hours the yolk was eaten and fry began chasing infusoria. The fry is a typical "surface living fry". It adheres to the surface film. It feeds on infusoria and minute Cyclops larvae. It grows rapidly and until they reach 15-20 mm, there seems to be no problem at all. But when they are of that size they mostly stop growing and never will grow larger. This is the common impression from the reports. Foersch and Sauer: fry grew to 20 mm, only a few grew larger. Hoffmann: fry grew up to normal size, however many were undersized - 15 mm only. Birkholz: his breeding pair did not grow larger than 30 mm, whereas his offspring in 4 generations reached 35-37 mm. Muller: her fry matured within 3 months, she does not write about undersized specimens. Nieuwenhuizen: he raised a large number of fry. 1/3 reached 20 mm, the rest remained smaller and were used as food. He had better results later on in soft water, but then he also fed pond infusoria.
Tek's stock
On 19 Aug. 59 Tek packed (in our normal 2 ccm ampoulles) 30 plus 25 eggs from his native stock of "javanicus" in two ampoulles. These arrived at Virum on 22 Aug. 59 and were at once removed into small glass containing my normal "rainforest water" - very soft and slightly acidic. Eggs were spawned on 17 Aug. 59 and first fry hatched on 04 Sep. Until now (07 Sep. 59) about 1/3 of the eggs did hatch. All fry have been ready in their eggs for many days. Tek collected this species about 1 kilometer west of Djakarta where he lives, in small ditches along the street and about 1/2 kilometer from the shore. Water was a bit brackish and is very hot during daytime. Current is slow. Color of water: little brownish. Bottom contains mud, about 1/2 a meter deep. Plants: lots of algae, Elodea densa, Ceratophyllum demersum, Najas species, Eichhornia crassipes, duckweed and now and then water lillies in groups. Along the ditches there were many Acrosticum aureum and Acanthus lilicifolius (bog plants). He saw many nests from Trichogaster trichopterus. He also saw Brachygobius doriae, Dermogenys pusillus, 2 Rasbora species, Clarias batracus, 2 Eleotridae species, Muglil oligolepis and lots of small shrimps. Tek also found specimens of Aplocheilus panchax and that little "Oryzias" species. Fry 4.5 mm.
O. luzonensis
Guillermo, J. (see "The Phillipine Journal of Science, vol. 77/1947) studied the breeding in this species. It is found in rivers, creeks, ponds, and ditches in Solsona, Batac, Laoag, Bacarra and Dingras, Llocos Norte Province, Luzon. Freshwater. Feed on mosquito larvae, plankton, and organic detritus in the litoral zone of the waters. Surface fish. In aquaria it is lively. D, A, and C have handsome yellow color. It is called "coscosleng" by the Llocanos. Breeds the whole year, with a maximum in Aug. It is found in large shoals in slow current along the shores where plenty of Vallisneria, Anacharis and other waterweeds are found. It prefers water depth of 1-3 feet. Female carries its eggs in clusters, it is smaller than the male. A female who is ready for spawning is very active and will be chased by several males. When it is time for spawning it slows down and it places itself on the gravel and rubs its belly against the gravel or small stones. Then the eggs appear one by one. Each female carries 5-28 eggs. The spawning act then takes place and the males follow the female. It carries the eggs until hatching or deposits them on plants. Guillermo gives data of a number of eggs in connection to the size of the female (size female in mm/number of eggs): 32/28, 31/28, 29/24, 30/26, 28/17, 27/26, 26/20, 25/14, 24/9, 22/5, 23/7, 21/5, 20/7, 19/5. Eggs hatch within 8-10 days in the laboratory. They measure 1.5 mm and are not circular. The fry measured 5 mm.
O. melastigma
Job, T.J. gives (Records of the Indian Museum. Vol. XLII 1940) the following data for this fish, native to his country. It grows up to 1 1/2 inch. It is found in freshwater as well as in brackish water in ponds, lakes, rivers, canals and creeks in the lower Bengal, Orissa and Madras provinces. It also has been reported from Burma (Wynaad), the Kiangsu province of China (?), Formosa (?), Korea (?), and Japan (?). He found eggs and gravid females in freshwater near Calcutta in the period Mar.-Oct., but the fish do breed most in June-Aug. During the Monsoon the rivers flood the surrounding land and he then found it even in small pools on the roads which had been flooded by rivers. Chatterjee found that it breeds through the whole year. Egg about 1 mm and is carried by the female fish in clusters on both sides of the belly. Also in this species there are short and stiff hairs on the membrane together with long and elastic filaments concentrated in one pole. 20-40 eggs. The female does not try to get rid of her eggs and they normally hatch before it drops them. Eggs hatch after 8-14 days but sometimes they need much longer. At Calcutta they hatched after 11 days at 31 C and 14 days at 29 ½ C. In a tank they hatched after 19 days at 29 ½ C but the water was not changed. The fry measured 4.0-4.5 mm just after hatching. They grew slowly on infusoria. After 7 days they were 6 mm long after 14 days 7.5 mm, after 3 1/2 weeks 10 mm, and after 6 weeks they measured 12 mm. His stock had a distinct yellow edge on vertical fins (matured specimens).
O. latipes
Job gives a few data. Female carries 50-225 eggs in her clusters. It tries to get rid of the eggs. Eggs hatch after 10 days at 25 ½ C and after 14 days at 23 ½ C. Rachow (AFiWuB = Aquarienfische in Wort und Bild): during summer the spawning takes place once a week normally. Eggs hang in clusters from the female's anus. 12-36 eggs normally. Eggs hatch within 4-10 days. Undersized offspring is the rule: about 15 mm only.
Questions
Breeders: we possibly have to find out:
| Copyright 2022 Richard J. Sexton |