There are 34,000 different types of fishes in the world. Some have evinced unique ways to raise their younglings - more unconventional than other higher life forms.
Observing a cichlid pair tending to their new-borns in one of my aquaria, I came up with the second instalment of the parental care series. This time, it is all about fishes.
The spin-off struck me in the very beginning. Thanks to Hans Christian Andersen and Disney, The Little Mermaid appeared in my mind as soon as I had started writing.
Not paying much heed to her elders, Ariel embroils herself in dangerous life events. The story does not set an ideal notion of good parenting for anyone. Tragic as the end may sound, in contrast, The Little Mermaid never portrays the evolutionary triumph of fishes in parental care.
Instead, the fish pair I am keeping for months does the job well. I was in breathing distance, just a barrier of glass between us. Unaware of anything other than safety of the fries, the bonded duo was constant in guarding the nest.
Their perseverance kept me stuck to the developing of the idea. As I delved deeper into this concept, overwhelming waves of examples kept presenting themselves to me.
So, without any further ado, let us have a look at parental fishes, caring, intelligent, bold and fearless - all in a single package!
Safety is in safe nest sites
It is said by biologists that choosing and making nests is the most primitive and the foremost step of parenting. Well, fishes have mastered this like any other.
From stinging surrogate animals to snail shells, mud burrows, floating bubble nests and cleaned flat rock surfaces out in the open, fish houses are bewildering!
The lungfish scoops out a shallow depression in the mud of a swamp, rich in aquatic weeds and grasses, which affords protection.
The bullhead catfishes are more partial towards submerged rat-holes for egg-laying. Air-breathing gouramis prefer to make a floating mat of sticky air bubbles.
Clownfishes resort to deadly anemone tentacles. Evolution gifted them with protection, but anemones are no easy affair for others.
The second step of nest-making requires a watchman. The fishes adapt this well. Often in pairs, the brood mother guards the eggs and fry from all danger.
The strategies tend to be species-specific, yet the rule is simple. While there are baby fishes at home, no trespassing is allowed.
The cichlids, the group where the very known tilapia belongs to, are some of the top-ranked parent guards. Size does matter to them.
For example, the pair I am keeping - convict cichlid, a meso-american species - took over the entire 35-gallon tank. Introducing any other fish during breeding, regardless of size and temperament, becomes a big no-no.
Large pelagic hunters, who do not make any nests too, are well-known for guarding. Snakeheads, as you may call them shoal and gojar, can put up a spectacular show during monsoon. While parents swim at slow pace, hundreds of fries trail rhythmically as if clouds are swirling in a breeze.
Momma's mouth - a refugium
For the fish world, scientists have coined a term – mouth brooding. This means there are some fishes, which are known to carry their young in their mouth.
When the fries sense any danger approaching, they see one safe house - mouth of the brood. Many species do this as a last resort. Many others are used to keeping the eggs just after being laid. Arowana and the African lake cichlids are the best at doing this.
Fries in this sort of breeding strategy are generally small in number, leaving the mouth-refugium only when they attain a certain size. You may begin wondering - do the parents eat anything in these times? Your guess is right. The obligate mouth-breeders do not take anything.
The underwater kangaroo
We know that kangaroos carry their newborns in their pouch. Well, the gill-breathers can have a similar tactic up their sleeve (or, should I say in pouch?).
Male sea-horses, sea-dragons and pipe-fishes gestate eggs in their belly pouches and carry them until they hatch. There is one catfish from Brazil, the Brazilian catfish, whose females during pregnancy develop a spongy and sticky belly.
The eggs, after being laid, stick to the cup-like belly-depressions on the mother. Thus, they always stay under watch.
Here comes the aquatic cuckoo
No different to what a cuckoo does, the cuckoo catfish lays eggs in other fish's nests. Native to Africa, they target nesting and mouth-brooding cichlids.
As soon as the male creates a diversion, the female lays eggs while the cichlid parents are busy warding off the interlopers. The catfish fries (only one or two) get into the mouth-shelter after hatching.
There they sustain on cichlid fries. And one day, after devouring all fries, when the poor cichlid host can no longer hold them in mouth, they emerge.
Story of the yearlings
Many killifishes have a lifespan of one year or so. They do the act of breeding very differently - unique than anyone can imagine. These fishes live in seasonal pools, meaning when they will be gone, their temporary pool will follow likewise.
But, that alone cannot stop life. The killis find a way and they bury their eggs under substrate. The eggs themselves can subsist on the least amount of moisture.
The extent is so extreme that these eggs are traded as plant seeds. Order one pack on Amazon, get them into your tank and be sure to have stunning killifishes!
The more the merrier
Maybe while reading this article, you are multitasking and having a platter of delicious hilsa eggs and thinking of the strategy fishes might take in breeding.
Hilsa is built for speed. There is no room for care or anything sluggish and soft. Yet, they do thrive. Shads, tunas and many other open-water fast swimmers lay millions of eggs.
Out of millions, merely 1% reach adulthood; a pretty handsome figure in a breeding attempt and a victory for the species. So, the strength herein lies with the numbers.
Fishes are not simple and primitive as they are seen - vulnerable out of water and smelly to many. Fishes have their own ways of wonder. Try petting a cichlid pair or order a pack of killifish eggs. Maybe try watching a snakehead couple with a swerving shoal of fingerlings. You will get the essence.