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Discussion Starter · #1 ·
OK, my Oto’s have been throwing off lots of eggs and I wasn’t surprised to see a few babies darting around in my community aquarium. What did surprise me was the absolute lack of fear they have. They rest in the most obvious places like the aquarium glass where there is easy algae to access and swim right out in the open like adults!

Now my tank is full of predatory fish like Neon Tetras and I was sure this was suicidal behavior until I watched more carefully. One of the baby Oto’s was perched on the front glass of my aquarium in perfect view. I was sure it was about to be a perfect single meal for a Neon! Sure enough, a Neon spotted it and went for the baby! But, as soon as it got to within striking distance it turned away! I saw three Neons make the same maneuver!

Now I began to think! After the Oto’s began spawning, I lost 4 Neon’s to a strange bloating disease. I was sure that it was some virulent disease that was about to run through my aquarium and wipe it out. It didn’t. In fact my remaining Neon’s are very healthy and I observe them spawn frequently.

OK what do you think? Are Oto’s poisonous? Did eating some of them kill my Neons? My observations say yes. What do you think?
 

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Don't their pectoral & dorsal fins have spines? (I haven't had them for a few years.) The neons might have "choked" on them if the fry became lodged in their digestive tract.
 

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I do not know for sure but the spiney theory sounds best to me... what I would like to know is how you got these guys to spawn?! I would love to rear some OCs, it appears to be quite the task to acquire healthy stock.
 

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Yes Otos have spines. They've been known to kill angelfish who've choked on them.

There are some theories that most if not all catfish with spines carry some degree of poison (not too many studies have been done yet, but there was a writeup a few months ago in one of the hobby magazine subscriptions I get, can't remember which?) but most would not be toxic to humans unless a person just happened to have an allergic reaction.

www.otocinclus.com is a great site full of all kinds of tips on keeping and breeding otos, for anyone who may be interested.
 

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Discussion Starter · #7 ·
Oto's seem easy to breed

I believe there are plenty of reports about Oto's breading in aquaria. My experience is typical.

I purchased 6 fish for algae control. One died and I bought 2 more. The fish "fattened" up rapidly in my tank which has algae growth. After about a week, the fish began to become very active, darting around the tank rapidly, especially at night. I began seeing eggs before I saw the fish mating. Eventually mating became very common. Two or three males chase a female. Eventually she rests on the underside of a leaf. The male surrounds her in the T formation that has been described a lot on the internet. They stay that way for about 15 - 60 sec. When they leave there are 3 or 4 eggs left behind. The eggs hatch in 48 hours at 82ºF. They are free swimming in another 48 hours. I could not get the babies to eat anything other than algae, which I could supply easily from my tank. They double in size in two weeks. At this size they seem to be immune to attack from predatory fish.

My tank was undergoing changes during this activity but here is some of the chemistry:

Total hardness 60 ppm
Calcium hardness 30 ppm
Magnesium hardness 30 ppm
TDS 70 - 100 ppm
KH 2 - 3 deg.
pH 7.0 - 7.8
NO3- 5ppm
PO4(-3) 0.1 ppm

I believe that the secret may be changing water conditions and possibly the time of the year.
 

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Pretty sure it's the spines. I brought home a spotted climbing perch that decided my ottos looked tasty. Found it the next morning with half the otto still hanging out of it's mouth. I cut open the perch and found the dorsal and pectoral fins of the otto sticking into it's mouth/throat. Lesson learned for me, read up on fish before bringing them home :).
 

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Like everyone else, i agree that it was the spines.

If ever you net out any otos, you may notice that the otos stick to the net a big.
 

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Discussion Starter · #10 ·
It is true that Oto's have spines; however,

they are probably poisonous as well.

Here are some links to articles that say all catfish have toxin in their spines.

http://www.cnr.vt.edu/efish/families/ictaluridae.html

http://encarta.msn.com/list_poisonoussurprises/10_Creatures_You_Didn't_Know_Were_Poisonous.html

http://www.fishmartinc.com/hc-toxins.htm

A friend of mine who owns a pet store agrees that Oto's probably do have toxin in their spines and handles them as if they bees or wasps.

My feeling is that you should be carfull handling any catfish.
 
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