Another reason to buy 10 or more 'Corydoras'

[GaryE]

The standard experienced advice for buying fish from the Corydoras group is to buy ten or more. These are intensely social creatures that thrive in the company of their own species.

We often don't have big enough tanks for that, but we should if we want the fish. Plus, they can be expensive.

I thought myself clever last year because I was passing through a city that had a great store, but I was on a budget. The store agreed to have a box packed and ready for me to grab when they opened, as they sell a lot online. A really nice guy went in early to have the box ready.
I bought 6 Hoplisoma cf. brevirostre, and 6 Brochis arcuatum, picked up the box and drove for another 9 hours. I could have bought a dozen of one species, but my thought process was that I could get them home, and breed them to make a proper sized group. This would have been a good plan, if I hadn't received all females. I'm guessing the guy in charge of catching them, who was worried about the trip ahead for them, decided to catch me the healthiest looking, most robust ones he could. In a group of Corys, those are the females.

Buying online and not being able to pick out the fish yourself is fraught with such dangers. I knew this store was good, and the fish are healthy as can be. The usual online health issues weren't my fear. As ornamental fish, these ones are lovely. Next time, I think I'll bite the bullet and either increase my chances by getting home much later (around here, you want to avoid driving "moose alley" in the dark) by picking the fish myself, or spend my money wisely and get a dozen.

A lesson learned, probably soon to be ignored...

 

[plebian]

In my experience "standard" advice rarely applies. While more is almost always better when it comes to "social" fish it really depends on the species or even the individuals themselves. Case in point, the "standard" advice for discus is to buy 6 or more. My first purchase was 4. Two of them paired up and spawned and there was no overt aggression from the pair toward the others whatsoever. Not so many years ago I purchase a group of 7. Again, two of them paired up but there was a third (a female) who disagreed vehemently with that arrangement. After hourly bouts of fighting between the pair and the unhappy female over a period of one month, I removed unhappy female.

When it comes to corydoras, I once had a group of 5 emeralds (or brochis splendens, whatever). They were perfectly happy as a small group, even frequently breaking up into two smaller groups to forage. One of them died a few months after purchase. The remaining 4 went on as before, sometimes as a group, sometimes as pairs/individuals. No change in behavior whatsoever. I've had as few as 3 serpae tetras (the last of them in the LFS) and they were also just fine. No aggression, no nipping, etc. In fact, IME the serpaes were far less aggressive than diamonds or silver tips, e.g. which I've kept in larger groups.

I don't think you can pigeon-hole species or individual fish anymore than you can pigeon-hole people, racially or otherwise. It's not that generalities don't exist, it's that evolution loves diversity.

 

[GaryE]

It's debatable. The mainstream 'standard' is one solitary Cory. The idea of 10 has been gaining traction as people gain more experience with Cory group fish. Observing their social nature has opened eyes.
I had a solo Cory live 12 years when I was a kid to young adult. It can be done. I regret how I did things now, as it can't have been a great life for a social fish. But the fish lived long.

We had a member who quoted a study on shoaling size (as large as possible) , but it was one study and was never corraborated by follow ups. So I go with my own subjective study of how these fish behave, and my approach falls on the they show more interesting behaviour in large groups. I've kept Corys in various sized groups for close to 50 years now - they've always been favourites.

Should we do this or that? In most cases, there is no correct answer. There is more of a philosophy of fishkeeping involved. The goal of the fish to to stay alive, and maybe to breed. Being alive is the big one. I don't think that's evolutionary diversity - that's basic. Diversity comes with how they stay alive.

What's the goal of the fishkeeper? That's what we discuss.

Shoaling is what we see in nature for this group, and that's were our attitude matters. What's a large enough shoal? Five, eight, ten, twenty, three hundred? Pick a number. That's all we're doing. My goal is to watch fish behaviour in my tanks, and maybe breed the fish. Saying we need ten Brochis or other Cory group fish is a guideline. There are no laws.

 

[TwoTankAmin]

Sometimes the numbers part is not so easy. I have 8 new corys coming tomorrow. You can see how mcu they sell for if you do a search for Hoplisoma sp. cw111. The lowest price I have seen for them is $200/fish. I have seen them much higher for the most part.

The only reason I am gfettoing these is because I have a buyer of the plecos I have spawning in my tanks and the total sale is a lot of money and I agreed to take 8 of the corys as partial payment. I am not paying anywhere near the $200 price because I gave my buyer a super price and he had acquired almost 100 of the corys. So, I got the import price from him.

Now I would have liked more. His initial offer was for 5 abut I insisted on 8 to get a bigger group. However, considering I really di not want to be getting new fish. especially that pricey, and had to set up a dedicated new tank for them, I was not willing to "buy" more than that. When he made the offer at first I said no, I did not want new fish. But considering the price I had to pay amd how pretty the fish are, I succumbed. "So many tanks, so little time. Since I cannot get more time I might as well get more tanks." DOH!

I have always boug my plecos in groups. 6 is my minimum and about 15 the max. For ethe ones with which I work the ideal ratio is 2/1 M/Fm. That is because she can produce a clutch of eggs about evey 2 weeks while he needs about a month from spawning to booting free swimming kids out of the cave. But then he may need to rest up and do some serious eating as he has been going hungry for most of that month. If he can slip out, grab something to eat and get back quickly he will try that, but his dadly duties outweigh his hunger mostly.

I suppose one could argue that money should not be the reason for getting fewer corys. If one cannot afford the cost of a group of 10 or more, maybe we should not buy any in that case? I have kept a variety of corys over the years but not for breeding as much as for there being in my community tanks. These cw111s I will see what I can do in terms of their spawning. But is is always their choice to do so not mine. My job is not to do things that might prevent or even discourage them from spawning. Pretty much all our fish want to spawn, but that in and of itself is not enough for most of them. They do need the proper conditions and feeding which is our part in the process.


The above vid and 45 moe oc corys in the wild can be seen here

edited to fix a bunch of typos

 

[Boundava]

Have mine in the 120, a mixed bag and probably near 50 of them. They don't mind and are happy with each other as company. When I can, I do add to the population.

 

[Innesfan]

Getting back to the issue of winding up with single gender purchases, I've run into this with many species where the supplier, with every good intention, selects what they think are the best but which wind up to be all or nearly all of the same sex. Most recently I ordered a dozen Pethia stoliczkana (the Tic-Tac-Toe Barbs of our youth) and wound up with 11 males and one female. When possible I try to give clear instructions about gender determination, which I did in this case, but either I wasn't clear enough or the instructions never got passed on to the person with the net.

 

[fishorama]

Sellers often want to give us the more colorful or robust looking fish but maybe the easiest to catch too. Sometimes they only have 5 or 6 left of a shipment by the time I see them & commit. & of course, tank size matters. I may not have room for a larger group of 12 or more. I've ended up with a less than optimal gender ratio for whatever reason.

I've felt bad when I have 1 or 3 of a species left but don't want to keep that kind anymore. I usually just wait out aging fish or maybe give then away to a better home. I also feel obliged to let them know they're old fish that may only live months but could live much longer. My most guilt-ridden species was a gift skirt tetra along with several other fish from my husband's moving coworker. He knew we took pretty good care of our fish & wanted them to go to a good home. Poor fish swam a few inches back & forth & seemed to have what I'd call neurotic behavior, it lived 2 or 3 more years...

Sometimes a group of same species behave in a different than the expected way. I had 10 sidthimunki (now ambastia) loaches in with 6 zebra (b. striata) loaches. They lived in 2 groups at each end of a 75g; 5 sids with a dominate female & 3 striatas with a "wimpy" larger female. They didn't fight at all & would mix at feeding time. It was a very surprising but interesting behavior that lasted for quite a few years.

 

[plebian]

The goal of the fish to to stay alive, and maybe to breed. Being alive is the big one. I don't think that's evolutionary diversity - that's basic.

Diversity is exactly how species stay alive and evolve. That concept is central to evolution. In your experience you must have noticed that fish have personalities, which is to say that individuals don't always behave exactly the same way under exactly the same circumstances. Most of my silver tip tetras, e.g. only feed from the surface or the middle of the water column, they will not browse the substrate. But a few do. It's the difference in the behaviors of individuals that allows a species to evolve to changing conditions, for example scarcity of a primary food supply or the arrival of a new type of predator. How individuals respond correlates directly with the probability of their survival, reproduction and the evolution of the species. That's basic.

You seem to agree that there is no "standard" regarding numbers of social fish (after mentioning its existence to begin with). You also state that you base your opinion on the observation of behavior, exactly as I pointed out in my original reply. Lastly, you imply there is a standard (more is better) while denying that one exists, which seems a weaselly way of trying to win an argument. All I was doing in my original reply was pointing out that while your implication that "more is better may be generally true", it is not a universal truth. There are none of those in nature.

 

[GaryE]

@plebian - Standards are for humans. This is what you seem to have misunderstood. Standards are for the hobby, and our attempts to keep fish in ways we regard as workable for them and us. There are no standards in nature, but our hobby isn't natural. It's keeping fish in glass boxes, often thousands of km from the habitats that made them (the fish, not the tanks).

If we look to nature, a basic small but viable breeding population is hundreds of individuals. We offer small containers, powered filtration, artificial heat sources, and tiny volumes of water. My Hoplisoma melini, in a 120 gallon aquarium, are in a fraction of the water and space they'd have in their real habitat. Not much there is natural, so by standards I refer to standard practices. It shouldn't be taken literally, as if nature had rules. Sadly, we only get to see a twisted, human created version of natural in our aquariums.

Keeping that in mind, I find my groups of ten plus Corys to be far more interesting to watch as far as their dynamics go than my groups of 4, which tend to be less active. I would like to see the hobby move in the direction of looking at shoaling fish less as individuals and more as members of social groups, as that's where I've seen them act in ways that were less stereotyped. What a viable social group is always ends up being subjective, since in evolutionary terms, it likely involves far more individuals than the resources we have can handle. We're always going to get a skewed view in home aquariums, but with larger groups, a better show.

I'd have to put myself in a glass house on the bottom of an Amazonian stream to be able to observe how these fish behave in nature. I'd have to be the one displaced - not them. But I can suggest new standard practices to try to get us closer. You can disagree with them.

 

[TwoTankAmin]

I made a mistake in my post earlier in this thread. It was 10 not 8 coming. It started with 5 but I insisted on more and it actually ended up at 10 after I posted above. However, I had to call off the pick-up/drop-off. I was in the ER by about 2 in the afternoon and left diagnosed with bacterial pneumonia.

We are hoping to reschedule for Sunday. The gent picking up is supposed to take his 28 fish and then another 40 he will ship the following morning airport to airport. He will come in time to help with the catching and bagging of the 40. But, there is a catch. The person who will be getting the 40 plecos is my best customer and in the Chigago area. He has a friend who works for Southwest Air in NY and who is able to arrange for the shipping so that things go smoothly. Unfortunately, that person is starting nursing School on Monday. So we really need to be a go for Sunday.

And I am now getting excited about getting the 10 new corys. The Pic below is from PlanetCatfish:

Pair, female left

@GaryE
Despite not having your 12 year cory in a group, keeping it alive on it's own for that long is not so easy to do. I doubt most here, including me, could do it. It is a tribute to your skill as a fish keeper from very early on.

 

[anewbie]

I have 30 sterbai in my 500; they mostly scatter about in groups of 5 or so; maybe i only needed 5 for a proper group

 

[GaryE]

I have 30 sterbai in my 500; they mostly scatter about in groups of 5 or so; maybe i only needed 5 for a proper group

I know you're joking, but scattering about is natural. If you watch video of Cory group fish in nature, I think it's relatively safe to say the behaviour will be scattering mixed with shoaling. From what I've seen and have been told by people who caught them in streams, the serious shoaling we'd love to see is often when they are traveling. They'll cover distance. That's where I daydream of a one foot deep thirty foot long tank in a house I don't have for it. If you hd pumps at each end and could switch the flow direction, I think you'd see cooler behaviour.

When they've picked a meadow to graz, what I've seen in video is groups of 6 or 7 foraging within sight of other groups. In most of the tanks we have, they can always see each other, so there's no effort there.

The exception for me ( and a sign of the evolutionary diversity Plebian mentions) was Scleromystax barbatus. Males hated each other and held turf. I had a lot of them in a 4 foot tank after they'd bred, and they did not like each other.

 

[anewbie]

I know you're joking, but scattering about is natural. If you watch video of Cory group fish in nature, I think it's relatively safe to say the behaviour will be scattering mixed with shoaling. From what I've seen and have been told by people who caught them in streams, the serious shoaling we'd love to see is often when they are traveling. They'll cover distance. That's where I daydream of a one foot deep thirty foot long tank in a house I don't have for it. If you hd pumps at each end and could switch the flow direction, I think you'd see cooler behaviour.

When they've picked a meadow to graz, what I've seen in video is groups of 6 or 7 foraging within sight of other groups. In most of the tanks we have, they can always see each other, so there's no effort there.

The exception for me ( and a sign of the evolutionary diversity Plebian mentions) was Scleromystax barbatus. Males hated each other and held turf. I had a lot of them in a 4 foot tank after they'd bred, and they did not like each other.

I do see tighter formation/shoaling with the Dianema urostriatum i have with them (i have 20); they are also a lot shier than the sterbai even though sterbai are naturally a shy species that avoid the front with the humans.

 

[GaryE]

My most consistent shoaling 'corys' are my melini, who are also inclined to stay at the back of the tank. They were juveniles when I got them and they've grown in the 6 foot tank, but they aren't trusting. My arcuatum are in another, 4 foot tank, my all female cory tank, and they hog the front glass while the cf brevirostris in with them are rare sightings.

 

[anewbie]

My most consistent shoaling 'corys' are my melini, who are also inclined to stay at the back of the tank. They were juveniles when I got them and they've grown in the 6 foot tank, but they aren't trusting. My arcuatum are in another, 4 foot tank, my all female cory tank, and they hog the front glass while the cf brevirostris in with them are rare sightings.

To be honest two interesting species i've had are eques - i purchased them after complaining the sterbai were skittish because another person said they were very 'outgoing' and he was right at least the ones i purchased; the problem of course is they are very expensive.

The other species i like are *lot* are pygmy. They will send a scout out to find a good place to graze; and then the whole herd will pick up and travel across the aquarium at mid level to the new location. With that in mind i kept a group of 10 or 15 with kribs in a 40b - the kribs of course attacked them and bit off a few tails as well as killing one but after about 6 months the kribs decided they were harmless - at that point the pygmy would graze infront of the kribs cave and when the kribs hearded the fry saround to feed the pygmy would follow them (the kribs did not mind if they mingled with the frys).