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Cyphotilapia gibberosa


Cyphotilapia gibberosa
Blue Zaire Frontosa Cichlid
蓝扎伊尔皇冠六间
Cyphotilapia frontosa is a fish from the cichlid family native to Lake Tanganyika in East Africa. C. frontosa is endemic to Lake Tanganyika and is widespread in the northern half of the lake, whereas the closely related Cyphotilapia gibberosa inhabits the southern half of the lake. Unlike many cichlid species C. frontosa is a pelagic fish and rarely ventures close to the shoreline. The species generally resides at greater depths (30–50 metres sub-surface) than most other cichlids and rises to shallow waters in the early morning to feed on shoaling fish such as Cyprichromis species. C. frontosa can grow to a significant size with even captive specimens potentially growing to 35 cm in length. The fish can live for over 25 years.
C. frontosa has distinct markings with 6-7 black vertical bars adorning a white or blue body and head and trailing fins with a distinct blue hue. The species also develops a nuchal hump that is more pronounced in older specimens. C. frontosa is a sexually monomorphic species, although the hump is occasionally more pronounced in males. As is the case with many of the cichlid species found in Lake Tanganyika, parallel evolution between distinct breeding colonies has resulted in several different colour variants developing. C. frontosa is popular aquarium fish and several naturally occurring colour morphs are frequently available for sale to hobbyists. Due to its size C. frontosa needs a relatively large aquarium, however, it behaves relatively sedately and is tolerant of both con- and heterospecifics. To house a single frontosa you need at least a 29 gallon tank. However frontosa do not like being alone. A single frontosa needs a cave to live in; this is to ensure the frontosa feels secure. If a cave is not present to satisfy the frontosa's need for security it will begin to attack the other fish in the tank. This is especially true with male frontosa. Female frontosa are more likely to be satisfied with ground territory. They are best kept with other cichlids or semi-aggressive fish. Frontosa are best kept in at least 150 gallon tanks (550 L). A 150 gallon tank can house 6-8 frontosa. Water chemistry and temperature should mirror those found naturally in Lake Tanganyika. The PH should be between 7.8 to 9.0 and the temperature of the water should be between (26-27 C). The addition of rocks, or other ornaments such as pipes, allow the fish to hide and reduce stress. C. frontosa is an opportunistic feeder in the wild and its diet in aquaria should consist of good quality prepared foods, frozen foods like krill and earthworms occasionally. When spooked, frontosa have been known to break thermometers, filters, and even crack tanks. Frontosa do not grow to the size of the tank, they will grow to about (18–22 cm).


布隆迪六间,鼎鼎大名的坦干伊克湖代表鱼种。俗称皇冠六间。是发现最早、饲养最为广泛的六间,主产于布隆迪境内,早在60年代末就为人们所知。它的特征是黑白间(也称栋线)对比分明,状态好时脸颊、胸鳍、腹鳍、臀鳍全是蓝色,尾鳍的后半部也是蓝色的,背鳍的外部边缘是蓝色,边缘内是浅黄色。它们是口孵鱼类。雄鱼的额头会有很高且圆润的突起,呈鹅头的头包状。由此我们可以很简单的辨认雌雄皇冠六间。雌鱼每次可以产下数十枚鱼卵,但是它们每次通常只能含下10~50枚左右。所以每次繁殖的损失率
从生物地理分布上去观看,六间和其他大部份湖中的慈鲷鱼一样,基本上全个湖域也有它们的踪迹,然而它们从不同湖岸采捕点获得的个体在形态和色泽,甚至于栋间上也具有分别,这些分别相信是六间鱼的祖先在最初开始到达湖中的不同栖息处对于环境和生态适应上的一些突变所做成,而这些突变经过一段长时间后又稳定地保存在不同族群的六间身上,这些不同族群的六间分布在特定的湖域中继续繁衍和保留它们在同一物种中的差异性,久而久之便成为一个同属所没有具备或不明显的特征。其实六间和大部份的坦干伊克湖慈鲷一样,充斥着非常多的种内多样性,它们在基因定义上依然是同一个属(genus),而且能够相互繁殖,这里繁殖的意思并不是杂交,因为它们并不是具有生殖隔离的不同品种,(注:生殖隔离是指相同或近似的物种遇到地理上出现的阻隔而不能相互交配,而杂交可以是自然或人为的,一般自然发生的杂交较人为的杂交须要更加久远的时间)而是只可以从鳞片、色泽、硬棘的数目、外观或身体比例去区别的种内差异性。
  如今,大部份六间业者或业余养殖者都采用Cyphotilapia gibberosa和Cyphotilapia frontosa去区分这种鱼。数年前,有两位日本鱼类学家曾经比较研究过从湖的南端和北端所捕捉的Cyphotilapia frontosa,发现在湖中北端的frontosa较南端的有较长的身躯,牙齿也较南部的更明显易见;而这些南部型的frontosa相对于北部型,它们拥有较短和高的身躯,牙齿也较为内敛,通常会在鱼唇的内部位置,而且在鱼鳍的生长幅度也有明显分别,南部frontosa的鱼鳍生长得更加延伸和修长,这种相异性有可能是因为湖中深度和水压的差别而形成。另一方面,在鱼体的侧线上,北部型的frontosa在前后侧线之间只排列了两行鳞片,但是南部型的就出现三行鳞片的排列,这个分别亦有可能是因为体高在演化时増长了的影响。就是因为发现这些差距的存在,后来业界便用gibberosa去统称南部带有上述特征的Cyphotilapia,而北部没有gibberosa特征的就继续沿用frontosa去作正式学名。事实上,现在仍然有很多地方是采用Cyphotilapia frontosa或humphead cichlid去统称所有在坦干伊克湖里的六间鱼。
  在略为认识Cyphotilapia gibberosa和Cyphotilapia frontosa的分别后,对于种内差异的区分便可以有一个初步的概念。正如第一段所述,坦干伊克湖是由四个国家所包围,每一个国家也有其湖岸,纵使可能彼此湖岸的长度不同,但在该湖所获得的资源量理论上是相若的,观赏鱼出口对这些国家赚取外汇异常重要,所以在这些国家的湖岸地区设置了很多捕捞点,这些地方可以只是存在数间木屋的不毛之地,也可能是一个小渔港或城镇。坦干伊克湖的慈鲷类因为有丰富的种内差异,所以一般也在学名后括上捕捞地点以资识别,如以Cyphotilapia gibberosa(Samazi)为例:Cyphotilapia是(genus/属)gibberosa是(species/种),最后的括号内是一个地方的名称(Samazi)。六间鱼除了上述两个种的特定分别外,也可以在这个定义上再分为三大型,这三大型的其中一种是北部型(North species),这个型的代表可算是从布隆迪(Burundi)湖岸不同地点捕捉的六间,它们有着frontosa的所有特征,而且最为容易辨认的一个特点是它们眼睛的第一条栋间是由上而下地贯穿眼睛,但是并不是北部型就等同frontosa,因为在地理位置上属于坦桑尼亚的奇高马(Kigoma),那里捕获的Cyphotilapia有着着明的七条栋间,但同样拥有frontosa的特征,所以七间的学名是Cyphotilapia frontosa(Kigoma)。另一个是坦桑尼亚型(Tanzanite),它们有着gibberosa的特征,而且大部份也产自坦桑尼亚湖岸不同的地方,但是在体色表现上它们会倾向于粉宝蓝或金属蓝色。至于最后便是萨伊型(Zaire),即现在刚果共和国的湖岸,这些地方捕获的六间有着明显的深紫蓝色表现,也是所有六间鱼中最多饲养者追捧的六间型,而在最南端赞比亚湖岸捕获的六间,其接壤刚果共和国地点的捕获种色泽上较倾向于萨伊型,但于Hore Bay附近的地点又较近似坦桑尼亚型。不过,无论是坦桑尼亚型或萨伊型的gibberosa,它们和frontosa的一个主要分别是第一条眼栋,gibberosa的第一条眼栋只会由上而下达至眼睛后便会向前方水平伸展,因而形成一个三角形,这是一个爱好六间者首先要学懂的分辨法,也是两种六间的主要外观差别。随着全球水族业的不断发展,相信未来会有更多新建立的捕捞点出现,而且将会有更多新的地域种不断引入市场令慈鲷爱好者有更加多的选择
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