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[APD] Otocinclus spawning

Last night I watched my Otos spawn for the first time, something I've never
actually witnessed before. This stuff might be old news for many of you, but
since spawning reports for Otos seem few and far between I thought I'd add
my observations for those interested.

I have several Otos (O. affinis, I think) in an 80 liter planted tank.
Yesterday morning I noticed nothing out of the ordinary. When I returned
from work in the late afternoon, the first thing I noticed was the two Otos
locked in the catfish T-position (male wrapped around the head of the
female). A few moments later they swam off frantically, leaving 2 eggs
attached to the aquarium glass. The male followed the female closely,
hovering around her whenever she stopped. Every 5 minutes or so they would
repeat the spawining act, either on the glass or on plants. This continued
all night until I went to bed but was not continuing when I checked again
this morning. A few facts and observations:

Tank parameters measured this morning -
Temperature: 24 C
Ammonia: undetectable
Nitrate: ~10 ppm
GH: ~4, KH: 3
pH: 6.6
Heavily planted, high light, pressurized CO2, decent water flow about 5
cm beneath the surface.

- Only 2 of the Otos seemed to take part.
- Eggs were deposited on almost any flat, smooth surface - Anubias leaves
and glass most often, less often on smaller leafed plants, once on the
heater, never on rock, wood, substrate, or grass. They prefered the
underside of leaves, but not always.
- They seemed to prefer depositing eggs in areas of water flow.
- Eggs were not always deposited following each mating. About half resulted
in no eggs.
- When eggs were deposited, 2 to 4 eggs deposited each time.
- Eggs are approximately 1 mm in diameter, slightly opaque, yellowish-white
- The female's ovipositor was much longer than normal, maybe 3 mm in length
or more. She wasn't noticeably gravid, but she's always been a bit of a
- I don't know how long this was going on, but at least 6 hours.
- My water conditions haven't changed significantly over the past couple
of days (though difficult to know, I don't test it often). I did a 50% water
change about 4 days prior, which I do every week. Otherwise things have been
very stable in this tank for quite a while. Normal daily fertilization
routine. Temperature hasn't changed.
- There is not a lot of visible algae in the tank but I've never
specifically fed the Otos. They just survive on whatever.
- Not sure if this is relevent or not, but yesterday (the day of the
spawing) we had our first major thunderstorm of the year.
- Amano shrimp and Lampeye killies both definitely eat the eggs, almost
immediately after. The shrimp quickly eat new eggs but seem to ignore eggs
more than a few minutes old. The Lampeyes are interesting - some of them
actually followed the Otos around, waited for eggs to be deposited, and
snatched them up as soon as they were. Not too surprising, they do this with
each other too!

The only eggs I could see this morning are a small number on the underside
of leaves. I'm not expecting any fry to develop out of this, but it was a
fascinating thing to watch, even if all they're doing is converting algae
into fish and shrimp food.

Anyway, hopefully that interests someone.
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