TIMELY MOVE

It is time to give fast developing ranchu fry more room. Right stocking density is crucial for grooming healthy and well shaped fry. At this stage, when the fry is around 1/2 inch (1.5 cm) no more than 100 per 3.3 sq.ft (1 sq.m) is appropriate. As the fry grows the stocking density must be adjusted. Again, since my set up is quite minimalistic and I do not have room for more water containers, I used my 120 gal (454 L) pond to accommodate the next project - a larger size nursery for the ranchu fry.

All it took was four bamboo sticks, four rubber bands and a 400 micron mesh to make a net. The net was suspended from the bamboo frame in the pond, keeping the water depth inside the nursery of 4-5 inches (10-13 cm). I added an airstone and a hose to constantly supply clean water to the nursery, pumped from the UV sterilizer (see my previous post "Filter Box Addition and Improvements"). Water pours from the hose into a "diffuser", a bunched up fine mesh, to keep the water movement to a minimum.

Since newly hatched brine shrimp size is up to 400 microns, I chose 400 microns mesh to keep them from escaping. Any finer mesh would get clogged more often with algae and the rest of the derbies.

AMONG KEEPERS

Two weeks since hatching, this ranchu fry is close to what I am looking for at this stage. Still, all attention is on the tail. I am eager to see how the tail will develop in the near future.

Ranchu on its sixteenth day after hatching

FIRST CULL - IT'S ALL ABOUT THE TAIL

Since the eggs hatched, I was culling any fry with deformed body as soon as I can identify it. But today, two weeks from hatching, I went through a major cull, ending up keeping only 40%.

The fry is now half an inch (13 mm) long. Even though the tail is now more or less defined, still, it is hard to detect its details and asymmetry between the tail lobes and shoulders, and the tail split. Today my goal was to select the fry with a straight body line and with the most open tail, which ideally should be 180 degrees, but not narrower than 160 degrees. The culling was done through looking from above. Below, I put together a few diagrams to illustrate what tail shape and development I was looking for. Misshaped tail is outlined in blue and should be the reason for disqualification. The photos are not of my actual fry and are used only for illustration purposes.

The next cull should be carried in about two weeks or when the fry reaches 6/8th of an inch (20 mm), and the tail is further developed with more details visible. I anticipate even greater reduction in numbers then.

Desired tail shape and
degree of openness 

Tail has no split in the middle

Single, regressed tail

Tail is not open. Red line indicates
degree of desired openness

Tail is not open and
is asymmetrical

Tail is open but asymmetrical 

TWO WEEKS OLD RANCHU FRY

Two weeks old today since hatching. The tails are almost fully open and some are looking fairly nice. First big cull will need to happen this or next week.

SPAWNED AGAIN

Started last night and continuing this morning another spawn is taking place. Sixteen days past since the first spawn. This time ranchu are spawning in my new media - artificial "hairgrass" plants (see my previous post "Thoughts On Mops"). I have attached weights to each rosette and arranged them in a group on the bottom of the pond.

What I like about this substrate so far is that the eggs are spaced evenly, which is very important for their development. The plant's leaves are spread out in all directions exposing eggs to a good water circulation and supply of oxygen. This "mops" will be very easy to remove after the eggs hatch without sacrificing any fry. Lastly this medium doesn't seems to be catching any derbies. The ranchu seems to like my spawning "forest" too.

Ranchu eggs attached to an artificial plant