Observations On The Spawning And Raising of A Member Of the Genus Parotocinclus Eigenmann & Eigenmann, 1889

by J. T. Morris 


he main problem when attempting to spawn a new type of catfish is aquiring enough specimens to form a viable spawning group, usually they arrive as a single specimen in a shipment, by accident, but I was fortunate enough to be in the right place at the right time, and aquired a group of twelve Parotocinclus types (nearest identification seems to be Parotocinclus britskii Boeseman 1974). when placed in a well planted and established aquarium they settled in well, feeding on lettuce and Tetra Tabs. The aquarium used was a 36" x l8" x 15" with undergravel filtration and a small internal power filter, heavily planted with Aponogeton sp. and Cryptocoryne sp., bogwood and small rock caves. Temperature: a steady 78o ; pH: neutral; hardness unknown but local tap water soft. Males soon established their own territory but females were allowed to roam freely.

Colour, size and shape is the easiest way to tell them apart: males have brighter, denser colouration, females slightly duller and heavy when roed up. The spawning site for this species was a clump of Aponogeton leaves in the direct flow of the power filter. Males cleaned the underside of the chosen leaf.

The colour of the leaf was critical, a light lime green. When this plant died back spawning stopped, though plenty of other leaves were available. Only when these plants grew back did spawning resume. When satisfied that the site was suitably clean, the female joined the male on the leaf. A clutch of twelve large 2mm sized eggs were laid on the underside of the leaf the male covering them each time as they were laid to ferilize them. No more than two clutches of eggs per female were laid. The eggs were exactly the same shade of green as the leaves.

Approximately five days later (time varied from batch to batch, but no later than six days), tiny light green fry made a frantic dash to cover (Figure 1). Two small yolk sacs were absorbed over the next 36 to 48 hours. After the yolk sac has gone, the shape becomes more elongate, the greenish colour disappears and the flesh now becomes transparent (Figures 2a, b and c) with black lines and dots. At this stage the fry are syphoned out in a shallow fry tank 24" x 15" x 8" deep. The only other fish in the breeding tank were a shoal of ten Corydoras pygmaeus (Knaaek 1966) which spawned freely throughout the aquarium. These were possibly the initial spawning trigger factor; sexual emissions from them in the form of sperm, milt, etc.

 

                                 

      Figure 1

Figure 1  

      Figure 2a

Figure 2a


Figure 2b

Figure 2b

 

   Figure 2c

Figure 2c  

 

 

First food taken was crushed lettuce coated in micro worm. Two weeks later the lines on the body thickened and the fins formed properly,  especially the adipose (Figure 3). Crushed Tetra Tabs and chopped white worm are taken eagerly. Colour still transparent with black markings.

 

                                                                                                                                                                                               

Figure 3

Figure 3

 

Figure 4

                      Figure 4                      

 

 

At the five week stage the fins are fully formed and the marbled pattern begins to form (Figure 4). At the sixth week the colour starts to resemble that of the sub adult (Figure 5).

 

 

Figure 5 (dorsal view)

Figure 5 (dorsal view)

 

Finally, they become perfect miniatures of the adult Parotocinclus (Figure 6). At approximately 25-30mm the basic background on males is yellow with green speckled black marbling with bright red edges to the fins. Females are virtually identical but not quite so brightly marked.

 

 

Figure 6

Figure 6

 

The first spawning from the first pair resulted in 20 young Parotocinclus raised to young adult stage. Four different pairs were obtained from the original twelve. The remaining four were immature males. The pairs spawn once a fortnight in a six week cycle and then rest eight to ten weeks while females roe up again. Youngsters from first spawning are now ready to spawn themselves (March, 1984), are in the process of pairing off (born 20th December, 1982).

Things to do to spawn and raise Parotocinclus.
1. Mature tank heavily planted with tall narrow and broad leaved Aponogeton sp. and Cryptocoryne sp. Bogwood for shelter.
2. Clean fresh water in the aquarium, regular water changes at least each week; up to one third of the tank.
3. Power filtration preferably internal, with out flow over tops of plant leaves.
4. Good variety of live and dried foods to help condition them.
5. Shoal of non aggressive breeding fish to help trigger them.
I found Corydoras pygmaeus ideal for this purpose.
6. Have plenty of micro worm and white worm on hand.

Things not to do or "How to kill Parotocinclus fry in 7 easy lessons!
Lesson one: Don't net fry from tank, syphon them into tubs to transfer to fry tank - very easily crushed in the net.
Lesson two: Fry tank should have water no deeper than six inches -too deep and fry cannot reach surface and die off.
Lesson three: Food in the shape of lettuce coated in white worm should be available constantly for first stages - fry starve very easily.
Lesson four: Change water up to 50% daily in fry tank - because of nature of food, water can foul quickly and kill fry.
Lesson five: Use only airstones in bare bottomed tank - fry easily sucked into filtration systems, even undergravel.
Lesson six: Use external heat to keep the fry tank warm, this can be done by placing fry tank directly on top of a larger, heated aquarium - heater/stats, especially the green types, seem to attract the fry with fatal results.
Lesson seven: Fry are sensitive to chemicals, use as few as possible -cure for Hydra in aquaria using a battery with a each end of the tank did not affect Corydoras, killed 50 young Parotocinclus.

Since spawning the original species, I have aquired a second species of Parotocinclus very like Parotocinclus jimi Garavello 1977, and the fry from them have proved to have the now typical lined and transparent first stage. Both Parotocinclus species laid on the plant leaves. The two recently spawned Otocinclus species preferred the undergravel uplifts and the glass sides of the aquarium. The transparent eggs and the fry are approximately half the size of the Parotocinclus. The fry once again bear a striking resemblance to each other in the first stages. With further study I hope to be able to tell if this is a coincidence or link between the two groups, Parotocinclus and Otocinclus.

This article was originally in the Catfish Association of Great Britain's magazine No.42.
Drawings by N. Q. Morris

 

 

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