Tuesday, November 23, 2010

Some thoughts on goldfish

Many of my readers probably have ponds (why? because you're wildlife people) and I suspect many of them have goldfish in them. I thought having done a post on sturgeon I really should also do a post on one of the world's most popular pets: goldfish; so here it is.

First up a couple of ground rules on the keeping of goldfish:
1) Don't release your goldfish out of your pond/fishtank into the wild. Goldfish are almost certainly not native to your region, they are very prolific, they will probably eat local wildlife and may hybridise with native species like crucian carp.
2) Don't release your goldfish out of your pond/fishtank into the wild. Seriously. I' sick of seeing them in wild ponds and rivers - and there are plenty of people that will take them if you make the effort to look.

So now we've got that out the way lets consider goldfish in ponds.

park goldies2

I think the first question is whether to put goldfish in your pond or not. There are reasons to go without fish, your pond may attract more wildlife without them - especially if it is very small when goldfish will tend to devastate anything coming in. You may also choose to go with something different; perhaps a native - sunfish in the states, various minnows and cyprinids in Eurasia, all sorts of cool stuff in aus. These alternatives are well worth considering..

If you do go with goldies in your pond then I think the next step is to take a genetic approach. Why? Well your goldfish will spawn and you will end up with a load of fry. I did in less than a month of putting 10 goldfish in my pond this year. As a result you want to think about attractive looking babies. You may also want to think about introducing fish from varying sources to try and add a little diversity to the gene pool.

young goldfish fry

As a result of this fecundity you want to think about introducing stock which will produce nice offspring. I've gone with a mix of Sarassa Comet types (red and white, long caudal fin) and common goldfish of varying shades of gold and red. I'm hoping this will result in the herd's offspring being attractive fish with deep reds, some having white markings and good fin development.I think a bit of white in the mix is good as it gives your fish some character and makes individular red and white fish easier to recognise.

park goldies

Try to steer clear of fish like the one in the middle with the black back when buying. Red and black fish may be very attractive but goldfish fry tend to colour up as they age by turning from black to red with the back the last to change. In other words this fish will probably turn red as he ages anyway.

For ponds one should also avoid the more elaborately finned fishes. Those varieties with double tails will invariably struggle to compete with other fish and to move around quickly enough in a large pond. I've also added some shubunkins. I suspect the orange goldfish will predominate in future batches of offspring with the odd orangey-looking shubunkin showing up too.

In terms of raising your goldfish offspring, in most ponds with plants they'll do it themselves. If there are no plants then the adults may canabalize their offspring but then nobody's perfect.

1 comment:

Floridacracker said...

Your fish look great. I was just cleaning the filter in our little goldfish pond yesterday.