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Re: How to Breed Otocinculus Affinis

Hasan wrote:

>Do otocinclus affinis breed in the aquarium?  I like to have more of these
>lovable algae eaters but they are not easily available in my part of the
>world.  I presently have some in a community tank.  What
>would it's requirement be? Water, temp, ph, environment, water depth special
>plants etc.....?

I have a pair of Otocinclus affinis that breed regularly, but I don't 
really know what the secret is...yet.  I haven't been able to find the best 
food for the fry either, so I've been unable to grow out any.  Recently, I 
redid the tank I keep them in and now my plants are having deficiency 
problems, so my Oto experiments have been put on hold temporarily.  Here's 
what I know and have observed so far:

Tank:  20 gallon "High";  heavily planted
Water (current):  GH: 6;  KH: 4;  pH: 6.5-6.8 (DIY CO2 injected)  Temp: 
24.5'C;  Depth: 12-13" surface to substrate
They have also spawned in an alkalinity of 5 dKH.  pH has been as high as 
7.3 and as low as 6.4.  I use tap water.

I do large water changes (40%-75%) once a week and it seems to encourage 
spawning behavior.  The change water is always 4-6 degrees cooler than the 
tank water.  Oto's like good water movement -- mine play in the output of 
the filter all the time and, besides eating, this seems to be their 
favorite activity.  I feed them vitamin enriched flake food (OSI) about 
once every 2-3 days and they love it.  I also have wood in the tank which 
they graze on frequently.

When the female becomes gravid and her ovipositor becomes "inflated", 
spawning is around the corner.  The "courtship" consists of the pair 
chasing each other around and doing a prolific amount of wiggling on the 
glass.  The pair form a "T" during the actual fertilization -- male on top, 
bending over the female.  This is done with the female attached to the 
glass in the usual fashion.

The female has always deposited her eggs on the tops of Bacopa caroliniana 
leaves in moderate water current.  Interestingly, most of the eggs are 
deposited on the same plant (stem), and only when she runs out of suitable 
leaves does the female move to another plant.  She also seems to spend a 
lot of time selecting the best location for her eggs in the tank.  She 
drops 1-3 eggs per leaf.  I have removed all of the Bacopa from this tank 
since the last known spawning, so it will be interesting to see where eggs 
are deposited in the future.

The biggest spawning that I know of produced 15 eggs and 14 subsequent fry 
(one egg was unfertilized and was either eaten or knocked off before I 
could remove it).  It takes about 48 hours for the eggs to hatch at 
24.5'C.  The fry remain attached to the leaves for awhile after hatching 
and then are usually found on the glass or on Bacopa leaves in the vicinity 
of their hatching site.  I not been able to keep a fry alive past 5 days 
after hatching.  There's just not enough of the right kind of algae in this 
tank to sustain them.  I have some ideas for feeding strategies and hope to 
try them out soon.

It'd probably be better to try breeding Otocinclus communally (like 
Corydoras) to increase the number of eggs and potential fry, but I'd keep 
the Otos in a tank by themselves so nosy neighbors aren't spoiling the mood 
;-).  Oto's seem to be quite territorial despite their small size and I 
suspect this fact may be one of the secrets in spawning them along with 
water quality and diet.  The Oto's I keep in community tanks have not 
spawned nor have they exhibited spawning behavior to my knowledge despite 
similar tank conditions.  The pair that do spawn live alone with the 
exception of shrimp.

A couple of interesting things I've noticed:  [1] The Amano shrimp that 
also inhabit the tank don't seem to take notice of the eggs or fry although 
these same shrimp eat snails (and everything else they can get their 
pincers on), and [2] the Oto's seem to guard the eggs -- when I get close 
to them or a shrimp wanders near to the "nest", they get really agitated 
and aggressive.  They keep station close to the eggs and always seem to be 
nearby the fry after they hatch.  Perhaps this activity explains why the 
shrimp ignore the eggs, but it all may just be coincidence too.

Phwew!  Sorry I got so long winded.  If there's anything else you want to 
know, feel free to contact me off list.
Chuck Huffine
Knoxville, Tennessee