Re: Corydoras, repro.  – 7/30/08
hi Neale,
thanks for that. three of the four came out soon after I got your answer but the other one was stuck longer. I was afraid to roll the egg in case I could damage the little guy inside. the other problem was that there was still an empty shell stuck to it. I tried to squirt water into the empty shell which gave the little one a bad roller coaster ride but later it came out on its own although it looks a bit disabled. I will see how it survives.
thanks again
Silvia
<It's the nature of egg laying fish that some eggs won't develop properly. Such fish have evolved to produce lots of eggs to compensate for the low chances of survival for each egg. You will likely lose quite a few fry over the next few weeks for various reasons; unless you're a serious breeder I wouldn't worry too much. Even if only one or two survive per batch, that's rather better than would happen in the wild! Good luck with the kittens, Neale.>

Re: Corydoras   7/31/08
hi Neale,
one or two sounds really very little to me.
<That's how Mother Nature works. If a pair of Corydoras produced more than a couple of fry that reached maturity, we'd be knee-deep in them pretty darn fast. Darwin worked this out using elephants. He showed that even allowing for the fact elephants breed extremely slowly, if every baby elephant survived, there'd be 15 million elephants within 500 years. I'm not saying you should aim for this with your breeding projects, merely resigning you to the fact that not every single baby fish can or will survive, and in the big scheme of things it doesn't matter.>
as I mentioned before I have done it before, I just didn't encounter this sort of problem before. usually I have about a survival rate of 75% after hatching for the Corys. this time I lost already about 60% of the eggs before hatching.
<Many things may be happening here. Fertility declines with age in many species, and inbreeding also reduces fertility. So if you're crossing siblings for example, you can't expect to have as many fry, or as many viable fry, as you would were you crossing unrelated wild-caught fish. Diet and water chemistry may be factors as well.>
when I started harvesting the eggs the female was already laying eggs for some 4 hours and was already pretty exhausted. the earlier laid eggs were already eaten by the rest of the community. that's life :)
<Yep, that's how my Corydoras breed, and the pufferfish follow them around snapping up the eggs like popcorn. I'm lucky if I rescue half a dozen.>
I assume that some haven't been properly fertilized and some didn't develop right for one reason or another.
<Could well be, but see above.>
even after so many times I always find it amazing to watch the fish lay eggs, and than those ones not been eaten, to hatch and grow. much better than TV :)
<Would tend to agree, being a person who doesn't have a TV set but does have three aquaria and a pond!>
cheers
Silvia
<Please do write with capital letters in the right places next time. Normally we send messages back for re-typing if they don't. But I was feeling nice. Anyway, good luck, Neale.>

Re: Corydoras 8/2/08
Hi Neale,
Sorry about the capitals. It's just a habit. A bad one I have to admit but thanks for being nice :)
<No problem.>
Good old Charles was right with a pair just to be replaced with a pair. In theory that is.
<Ah, he was simply making the point that without predation, disease, competition, starvation, etc. populations of any organism have the potential to increase exponentially. What he wanted to make clear is that something happens that prevents this, what he called the 'struggle for life'.>
In reality it doesn't work like this since homo sapiens has it's hand in it. We seem to be able to wipe out many species, sometimes before we even discover them. Most of that due to irresponsibility, disrespect and out of ignorance. The Australian Government introduced Gambusia into the river systems to control mosquitos, ignoring that we have the best mozzie control already with our beautiful rainbowfish. It has devastating effects on all native wildlife. When we are going out to do surveys of the creeks and rivers we sometimes find bodies of water only with alien, non native fish. We means members of ANGFA (Australian and New Guinea Fish Association, check out our website www.angfa.org.au) . The other end of the scale are people who keep or release predatory animals into an environment that they are not native to. My garden is abundant with wildlife but I often fear for them because my neighbour is not willing to keep her cat inside. Cats are introduced to Australia and I keep mine inside all the time.
<I know a few people who are in ANGFA, and they do sterling work. Bruce Hansen wrote an excellent chapter on Aussie fishes for my Brackish book. I'm glad you keep your cat indoors. As a cat lover, I've always felt guilty about the death toll cats inflict on wild birds. They are Nature's perfect killing machines, and in environments without predators and competitors, they can (and usually do) cause major problems.>
Back to the Corys. Being a scientist I am happy having more than two surviving which might help to keep the wild population survive. Especially since specimens in captivity don't have the life span they could have. I remember a friend buying a sterbai because she liked him. I tried to point out that he needed company but she thought he was fine since he came out feeding.
<Sad.>
I showed her my Corys who are all over the place during the day but it didn't make a difference. She only had him for some nine month. Mine are now about five years old and still happy. The female albino looks like she is fattening up again only after two week since she laid eggs. The kittens are doing fine. Using the word kitten is very unusual for me. I know that the English and the Americans are using it but if I use it here I get weird looks.
<What else you call a baby cat but a kitten?>
Cheers
Silvia
<Cheers, Neale.>

Re: Corydoras... larger issues...   8/5/08
Hi Neale,
<Silvia,>
I am probably not the average person. I read Darwin but I don't own it. But that was some 30 years ago and I noticed that I often read things others wouldn't and don't read what they would. I am a geologist but haven't worked in the field. You could say "conflict of interest". I didn't want to be in a position where, say, I had to sign off on a big dam from a geology point of view and disagree because very old historical heritage would be destroyed or a habitat for fauna or flora. Initially I wanted to do ethology but the lecturer put me off when he came in with a bucket full of baby sharks for dissecting. I was not keen on that part anyway but when he said that they are ONLY sharks I lost it. I happen to love sharks, so that was the end of it.
<Too bad. It's a common problem at university that you get exposed to science through the interests (or biases!) of the lecturers. Where I did my zoology degree most of the people studying invertebrates were doing so from the perspective of invertebrate pests and parasites. I got so cross with the lack of balance I ended up complaining to the head of department! But the reality is that most invertebrate biology is done from precisely those aspects. Most of the money in insect research is in pesticide development or malaria transmission or whatever. Most of the people studying nematodes are parasitologists, and so on.>
I worked for an environmental organization I helped to found after I left uni. Due to various reasons we moved to Australia some ten years ago. And here is where I can make you again jealous, not really on purpose though. We live about 20 minutes away from the beach. So I have good access to estuaries and mangroves but I can assure you crocs are not a problem down here. The Gold Coast, that's where we are, has a lot of canal frontage developments and they attract bull sharks. I wouldn't want to mess with them, though. We didn't choose this area on purpose. My husband just happened to get a job here.
<I'd tend to treat Bull Sharks with a certain degree of caution, too! They do of course swim into completely freshwater habitats, and likely account for most shark attacks in rivers.>
I was never involved in fish keeping till my children joined the science club a teacher offered after hours. I joined as well in the hope to train my English skills. It turned out that the teacher was not very knowledgeable. She asked the children one day to bring in an empty 2l (~1/2 gallon) juice bottle to make an aquarium. She supplied the sand, the weed and the fish. I can't remember what the weed was but the fish she identified as guppy. Her recommendation was that they can find more in the drains or to release it once they don't want it anymore. I got a book about the wildlife around this area and identified the fish as Gambusia. Little did I know about the laws. Later we went fishing with the kids under a nearby bridge where the river is close to the sea which means it is brackish.
<A-ha! Brackish water is often superb for catching small fish because so many marine fish lay their eggs there, or spend their first few months there as juveniles.>
We found tiny Monos and scats which we kept. Unfortunately we kept predatory "shrimps" with them. I later brought the Monos to a pet shop because they outgrow the tiny tank and I had no idea how to create a brackish water system. The guy from the pet shop sold them in his marine section. At that time, when I started to explore fish shops, I was taken by the tropicals around. You hardly find natives in the shops and often only in the feeder fish section.
<!!!>
It seems people are more drawn to the "exotic" ones. Ours are only exotic to others. But I have to agree what we have in our rivers here is amazing and can match any South American or Asian. But isn't it that the average people want a piece of exotic in their living room, like an exotic place where they would go on their holiday? My experience is that people often don't appreciate what they have around mostly because they don't know any better.
<I would agree with this. There's also legal complexity, making it difficult for someone who is inexpert to know where they can catch their fish or which species they can keep. Simply finding habitats with small fish isn't always easy, and then you have the problem of identifying the fish and obtaining information about their diet, social behaviour, etc. But on balance, I do agree that it is somewhat bizarre how little native fish are appreciated in many countries. Here in the UK we have a lovely diversity of marine fish and invertebrates thanks to the confluence of cold and warm water currents. We even have seahorses! And yet people very rarely keep British marine species in aquaria.>
We didn't go for holidays for years. After I joined ANGFA we started do go to the field trips and it is a very nice holiday for us. We are together with nice people, go to places where we wouldn't go otherwise and see nice environments. For us these are exotic places, too. Another field trip is coming up in two weeks and I am looking forward to it.
<Cool.>
I love to have the geckos in the house because they take care of the cockroaches. "Natural pesticides". I don't like to spray with the fish tank around and I don't like to do it outside neither. I use the weeds to feed the guinea pig.
My experience with Ancistrus is that I have a much better output when I leave him to do the work rather than hatch the eggs without him.
<Broadly yes, when fish are left to rear their eggs, they tend to do a very good job, oxygenating them and removing fungused ones more delicately than we can manage. There are some species though where inbreeding has short-circuited this, most notably Angelfish.>
Cheers
Silvia
<Cheers, Neale.>