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Re: [APD] Otos



I was adding Stuart's link to Planet Catfish to my file on Otocinclus when I found a post from APD on breeding Oto's. There is most likely a lot more info in the APD Archives. Search via Google Advanced Search limiting the domain to Actwin.com and look in the text only for more Oto info.

Here is what I saved as a Word Document:

Jerry Smith

Message: 1
Date: Wed, 28 Jun 2006 10:48:29 -0600
From: "Mark R" <oldsan at gmail_com>
Subject: [APD] Otocinclus spawning
To: "aquatic plants digest" <aquatic-plants at actwin_com>

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 spawning 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 preferred 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 tint.
- 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 fatso.
- 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 relevant or not, but yesterday (the day of the spawning) 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.

Mark.


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