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Synodontis nigriventris


Synodontis nigriventris
Upside Down Synodontis
非洲倒吊猫
Upside-down catfish, Synodontis nigriventris, is a species of catfish. It is particularly noteworthy because of its habit of swimming upside down most of the time. Upside-down catfish originate from the Central Congo basin of Africa.
Upside-down catfish are small, reaching a maximum of 9.6 centimetres (4 in). Like other members of the mochikidae family, they have large eyes, a large dorsal fin and three pair of barbels. Upside-down catfish are adapted to spend most of their time upside-down. This is reflected in the fish's pigmentation—their bellies are darker than their backs, a form of countershading.
These fish are mostly nocturnal, and feed on insects, crustaceans, and plant matter. These fish lay eggs. The young fish do not swim upside-down until they are about two months old.
The upside-down catfish is well suited to aquariums because of its small size (typically 9 or 10 cm or less) and peaceful demeanor. They should be kept in schools of 3 minimum for best effect. They should be fed a variety of good quality flake food, tablet food, frozen bloodworm and livefood as daphnia. Provide caves or ledges to them to loaf in.

Synodontis nigriventris is occasionally confused with S. contractus. However, on close inspection the species are easy to tell apart as Synodontis nigriventris lacks the large head and mouth and larger eye of S. contractus. 

The scientific name nigriventris refers to the fact that the belly of this fish is darker than the dorsal area. This is a form of camouflage, making the fish harder to spot by predators above, such as predatory fish, birds etc. It is a basic reversal of the colour scheme many other species use for the same purpose. The theory is that as Synodontis nigriventris generally feeds from the surface in areas which are heavily vegetated above the surface, it is more important that it can see what is going on below it and thus it has evolved to swim in this way. 

This fish spends up to 90% of its time in the inverted position and there have been several scientific studies conducted regarding its postural control. It was discovered that neither the swimbladder or inner ear mechanics (used for balance) were different to those in other fish. Changes in gravity also appear not to affect the fish. However, what was found, is that the relationship between the central nervous system and the inner ear organ is somewhat unique, and has a self-regulating capacity which essentially "resets" whenever the fish tips beyond 22°, allowing the fish to remain stable. 


反游猫属于鲶形目倒立鲶科(Mochokidae),是一种非常趣怪的热带观赏鱼类,它的色彩和体型都不是很美丽,但吸引人的是它游动的姿态--当它们明目张胆地肚子朝天敏捷地游动地时候,只要是看到的人都会发出一声惊奇的感慨,这也是反游猫吸引了众多水族爱好者饲养它们的原因。
反游猫属于鲶科的Synodontis属,有许多不同的种类,色彩以及体型大小也各有差异。在饲养方面因为这些不同的种类不同的出产地,因而水质要求也不尽相同,大致划分为两类:
1.河川型反游猫:主要是指产自西非尼日利亚湖、尼日尔湖以及萨伊水系的反游猫。常见的种类有:满天星反游猫(S.angelicus)、黑翅反游猫(S.schoutedeni)等等。
河川型反游猫在弱碱性-中性-弱酸性的水质环境都可以良好生活。其中一些小型种类不喜欢饲养环境中有过于激烈的水流,而中、大型种类却非常偏好,同时,这些中、大型种类也具有强烈的底砂挖掘能力。河川型反游猫长着细小的牙齿,它们会啃食沉木、岩石上的藻类,或是水草,它们的肠胃可以消化这些植物性饵料,但是它们其实并非是藻食性鱼类,它们是杂食性的,它们也会吃一些小鱼、小虾、昆虫以及新鲜的活饵,但动物性的饵料最好不要作为它们的主食。无论如何,最重要的是:喂饲的饵料要注意营养均衡,品种多变。同时,这些食量很大的鱼儿最好每天喂饲1-2次。
2.湖泊型反游猫:主要是指产自西非坦干伊克湖、马拉维湖、维多利亚湖的反游猫。常见的种类有:花点反游猫(S.nyassae)、维多利亚反游猫(S.victoriac)等等。
和非洲慈鲷一样,湖泊型反游猫适合的生存环境是碱性且硬度较高的水质环境,这是非常重要的,因为水质要求一旦不适宜,这些可爱的反游猫将无法展示它们独特的魅力,更不用说长久生存下去了。在食性方面,湖泊型反游猫和河川型反游猫差不多,但喂饲过多的红虫、赤虫等高蛋白动物性饵料也是会致命的。
在饲养反游猫的方面:除了挑选合适食性、水质、温度以习性及要求的鱼类与之共养以外,更要注意体形大小是否过于悬殊,通常小型的反游猫种类的习性都是非常温和的,而一些中、大型的反游猫种类的习性会相当暴烈,甚至有极强的领域性,会经常发生冲突争斗。因而,在饲养它们的水族箱中,以沉木、岩石或其他装饰材料为它们构置一些隐蔽场所会更有助于它们的生长。
在饲养反游猫的疾病方面:通常反游猫的体质在鲶科鱼类中是比较强韧的,而河川型反游猫比湖泊型反游猫的适应能力更强。反游猫最常见的疾病就是白点病,但作为对药物作用抵抗力极强的它们是应该很容易治愈的。另一点是反游猫都喜欢亚硝酸盐极低的水质环境,因而在水质开始恶化的时候,反游猫会有一些特有的对水质恶化的病兆表现。前期会表现为:体色变黑,没有光泽、双眼浑浊……此时就应该小心谨慎了!应该立即更换1/2容量的水,以及配合治疗细菌、治疗生虫的药剂进行急救措施。一旦转入症状后期,发生的死亡率就会非常高!表现为:口部发红、鼻孔上仰、触须下垂、有气无力……此时就可以说无药可救了。
反游猫的雌雄鉴别和繁殖都非常困难。根据一些国外资料显示:一些种类的反游猫会在产卵季节,将鱼卵借助于口孵性慈鲷代为孵化,而这些鱼卵不慎被口孵慈鲷将自己所产的鱼卵一同含入嘴中孵化的结果就是,它们会提前孵化,先行孵化的反游猫幼鱼便开始吞食尚未孵化的慈鲷鱼卵维持生长,等生长到一定程度,自慈鲷嘴里游出来的时候,慈鲷的鱼卵反而所剩无几…
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