Otocinclus arnoldi - Spawning

[OregonOutdoorsChris]

It's been an incredibly exciting week for fish stuff in my house, as my Otocinclus arnoldi have spawned! I've already documented much of the details in the Breeding Log: https://www.planetcatfish.com/common/my ... es_id=6961 but figured I'd share some extra details and videos as well.

On Monday I moved a male and female Otocinclus arnoldi into a tank I had been preparing for just them. Thanks to working from home, I was around the next morning to see what appeared to be the start of courtship/spawning, and so little else got accomplished for the next several days as I sat nearby with a camera .

By all indications, they seem to spawn a lot like C. paleatus, preferring temperatures at or below 75F/24C. They're unfussy about pH, with my tap being fairly standard municipal water of a pH in the mid-7s, and I do nothing to alter it.

They produce very small eggs of just barely 1mm in diameter. Which now that I know for certain what their eggs look like, I believe I have seen their eggs in the community tank they were in previously, but in that other tank the eggs were quickly eaten by the various community fish.

On their first pass, a dozen or so eggs were distributed fairly evenly throughout the tank, but they eventually came to favor the glass of the tank which gets sun from a south facing window, and ended up laying the bulk of maybe around 100 eggs there. The location might just be a coincidence, but my hypothesis is that maybe they feel that location will offer the fry more food. Idk.

I did not remove the eggs from the tank for this first experience with them laying, and have been rewarded with several dozen fry having hatched by this morning. Though there was some fungus-ing of the eggs, so in the future I will experiment with removing and treating them with methylene blue.

Pre-Spawn Courtship & Cleaning Spawning Eggs shortly before hatching Hatchlings Now onto the next adventure of rearing the fry... I'll do my best to report back with my experience.

[bekateen]

Awesome sauce! Congratulations!

Cheers, Eric

[Jools]

Those videos are great, I find video of spawning tanks are really helpful for all levels of fishkeeper. Good luck rearing the fry and I look forward to hearing, or seeing, how you got on.

Cheers,

Jools
PS Good to see it's the real

Otocinclus arnoldi

too. They're often misidentified.

[Shane]

Fantastic write up and documentation! Well done.
-Shane

[OregonOutdoorsChris]

Thank you everyone.

The fry seem to be doing well so far, with what seems to me like a fair amount of growth, but granted it's only been a couple of days.

Compare freshly hatched on the 8th

With today the 10th

same camera zoom in both photos.

[bekateen]

Great!

Dude, you've got some seriously green algae there! No wonder they're doing so well.

Good luck,
Eric

[OregonOutdoorsChris]

Dude, you've got some seriously green algae there! No wonder they're doing so well.

Unfortunately no green water, since all my tanks are in the living space I have to keep them at least somewhat aesthetically pleasing, and I'm pushing my luck as it is by leaving all the brown algae on the glass.

The green was just a blurry sword plant in the background, here's some other photos I took at the same time in a different part of the tank.

[OregonOutdoorsChris]

At 7 days old, they continue to grow with very little input from me. Each morning and evening, I feed a pinch of repashy soilent green powder, a pinch of spiralina flake I roll between my fingers to grind up more finely, and a pinch of freeze dried copepods. Whether the young are eating any of that, or are otherwise just making do with the naturally occurring aufwuchs in the tank, I don't know.

I also now have multiple age classes present. I would guess that the larger fry in this photo is probably around 4 days old, and the other is freshly hatched. The adults seem to have a round of egg laying every 2-3 days.

[Jools]

What age are the larger ones now?

Jools

[OregonOutdoorsChris]

What age are the larger ones now?

Jools

The photo of the biggest one is at 7 days.

[OregonOutdoorsChris]

To keep any interested parties informed of how things are going, sadly I had a major die off of fry this week. I think I got a little too overzealous with the feeding and as a result water quality suffered. Fortunately, there's still a handful that have survived, including what appear to be some from the first batch of eggs, so it isn't a complete set back. But it sure took the wind out of my sails when I went from too many fry to count to you can count them on one hand.

[bekateen]

Dang, sorry Chris. But don't feel too bad. I've had so much die off from all my Rineloricaria eigenmanni and Trachelyichthys exilis spawns it's almost numbing. But as long as at least a few are surviving, it's worth it and hopefully we get better with experience.

Keep it up.
Eric

[OregonOutdoorsChris]

There are still a few fry around, but as they get bigger they are becoming harder to find as they venture throughout the entire tank more like the adults, but in miniture.

I finally got some not so blurry photos of the adults for the catelog too.
Male:

Female:

And in another stroke of terrible luck, I lost the second female I had. I had moved her into a bare bottom tank to condition her before introducing a male, with the intent to then try to rear a second set of fry in a slightly more controlled situation. Sadly she inexplicably died two days later. So now the pressure is on to get this first, and now only, group successfully producing, because this is now the only female I have.

[OregonOutdoorsChris]

I got a little bit better photo of the approximately 3 week old fry

The adults have spawned another large batch . I did a cool water change two days ago, and so if that triggered it, it was quite delayed in comparison to how corys seem to react. Of the eggs I can see there are about 100, and who knows how many more on the sword plant and in the back of the tank:

And interestingly, maybe around 5% of the eggs were laid with a defect of some sort:

From the first batch these seemed to fungus over especially quickly, so I'm doing my best to remove the obviously defective eggs.

[OregonOutdoorsChris]

The next wave have hatched.

From laying to hatching was a little less than 48hrs.

[bekateen]

They're tiny!

[OregonOutdoorsChris]

They're tiny!

Indeed, and it's mind blowing how quickly they grow too!

[OregonOutdoorsChris]

Interesting, and that last wave of fry had a sudden die off today. Went from dozens of fry yesterday to few-to-none this evening. This is 8 days after hatching, which is about the same amount of time that passed on the first batch till their sudden die off.

I was more careful about not overfeeding, and haven't fallen behind on water changes. Which makes me wonder what is going on and pondering what variable(s) to try changing next. One thing I'm considering is adding leaf litter, though the fry generally hang out at the top of the tank, so I'm not certain about that yet.

[bekateen]

Sorry, man. That's too bad. Adding leaf litter is a good idea. Maybe also Spirulina powder or wetted Repashy powder (not prepared, just the powder mixed in water so it sinks).

Good luck!

Cheers, Eric

[OregonOutdoorsChris]

This has been a rough last month. Something went wrong with my tap water, some sort of foamy substance after a series of major rain storms. Before I realized there was an issue, the 4 remaining fry from the very first round of eggs, and which had gotten quite sizeable so I thought were out of the woods for any further loses, were all lost. The adults stopped eating, were acting stressed, and as expected were showing no further breeding behavior. So then I was stressed, second guessing every move and worrying about whether the next water change was going to help or hurt.

Fortunately the water quality issue seems to have passed. The adults are slowly getting back to eating. And to my absolute joy, I do appear to have a surviving fry! Given the size, I would guess this actually came from the very last batch of eggs about a month ago, so I'm stunned at how this one made it but its larger/older siblings didn't. Regardless, it gives me hope.

It seems to enjoy sweet potato...

and I chuckled when I saw it on top of the Hisonotus this morning, it reminded me of the children's book "Are You My Mother?"

[bekateen]

Ugh, what a story! Glad you have one little survivor.

Better luck going forward!

Cheers, Eric

[OregonOutdoorsChris]

Sadly my last male died the other day, leaving me with one lone female. Its death was rather unexpected as he was looking quite healthy, feeding normally, and swimming normally, then the very next morning was dead floating covered in fuzz.

Though one last observation on their breeding behavior, I suspect that the female may sometimes initiate courtship. Over the last year when I'd sit and watch for a while after doing a water change, I'd sometimes see the female, often while extremely full of eggs, bumping the male near his vent as if to try to initiate the T-position. In retrospect, maybe his disinterest in her was the sign there was something not quite right with him, and what ever it has now finally caught up with him.

Unfortunately no fry ever made it to adulthood, but I sure learned a lot in the process. So unless by some stroke of luck imports begin from that region, I expect this is likely to be my last update on this.

[bekateen]

Dang, sorry for your loss.