It is almost exactly one year since I placed the first koi in my ponds. I placed 94 fish in the two ponds initially and then bought 4 more in the weeks following that initial stocking. I added 6 grass carps, also fingerlings in October.
In the veggie pond I placed 34 goldfish, 8 vlei kurpers and my son "dropped" 4 Oscars and two funny barbel like things in the veggie pond as well.
I placed 8 Platies and 8 Mollies in the final filtration trough. All of these fish were placed in the system in the first 4 weeks and then I placed a strong prohibition on any new fish into that system.
The veggie pond and filtration inhabitants was done for specific reasons, each of those species had a task. The goldfish are extremely effective in cleaning up algae growth. The Platies and Mollies were placed into the system to control the mosquitoes and the tilapia was earmarked to help with algae and other water insects.
Many people, including my own family was of the opinion that I have lost my mind and were unrealistic to think that I will be able to get a self sustaining eco system going.
I battled with algae and mosquitoes and "muggies". But in the meantime the mollies and platies started breeding and by late November the presence of the "muggies" and mosquitoes in the final filter chambers and sump was almost non existent. It was also around this time that I noticed the first small kurpers appearing. The gold fish was also spawning but I noticed very few actually making it to "fish" in that veggie pond. I think between the other goldfish, the kurpers and the oscars the fry did not stand much of a chance.
My plants were struggling because the bio mass in the ponds was too low to sustain them and I was forced to add fertilizer. I used seaweed extract and twice a week we poured around 100ml of a double diluted mixture into every pot. This helped the plants but also fed the damn algae.
In July I bought two earthworm farms from a guy in the Cape and by late October the worms were beginning to produce around 3 litres of "tea" per week. Diluting this 10:1 meant that every week I had 30 liters of organic fertilizer of the highest quality. I started feeding this to the plants both in the pots as well as spraying the leaves. The spray has one huge advantage in that it basically wipes out all sorts of critters that wanted to eat the plants. The most important thing is that this worm tea is completely safe for the fish.
During November and December I lost two koi to what is believed to be dropsy. 2 of the grass carps in the veggie pond also disappeared and only 3 oscars made it to 3 inches.
Now remember all my koi was placed in the ponds as fish of around 70mm long. These fish looked almost lost in the big ponds but I calculated how many big koi could be sustained comfortably in each pond and then stocked those numbers. My idea was that the fish must grow into the ponds.
By late December I began to see the plants were needing less feeding and in January I stopped feeding them all together. The koi was now around 100 to 120mm and the increase in bio mass was obviously beginning to show it's effect in the nutrients that became available to the plants.
By this time my water was crystal clear and this is when I began to notice goldfish in the koi ponds
The only way they could get there was through the pumps. Initially I netted a few of them and placed them back in the veggie pond. I also noticed mollies in the veggie pond and the only way they could get there was through the pumps down the whole koi pond system and finally into the veggie pond. Quite amazing to me. They did not hang around in the koi ponds and followed the streams back to the veggie pond.
In April I noticed that there was a really big population of kurpers in the veggie pond and a few in each koi pond. I am sure I am going to see a huge population explosion of kurpers in the Spring. The original 6 is now the size of my hand. I will harvest the kurpers for my own consumption but I am afraid that I may be forced to introduce a fairly aggressive predator into the system to contain the numbers. I am not too happy with the other species in the koi ponds and I am planning to net them all out in Spring and place a fairly big Blue Kurper in each pond to sweep the fry up that pass through the pumps. I initially considered a bass but the problem with bass is that they grow fairly big and a bass will grab anything that fit in it's mouth and that will certainly also stops me from ever again place small koi in my ponds. If anyone has any advice on a good predator I would like to hear it.
I am sure that all of you can imagine the huge frog invasion I had to live through during Spring and I have made peace with that. Frogs are vital in nature and they are under threat. They are also an indicator specie and for that I just tried to scoop out the bulk of the eggs in the mornings while still allowing a fair number to remain in the veggie pond. I have seen how the tadpoles devour algae in my filter chambers and along the edges of the ponds so they are obviously part of the system and I need to accommodate them.
In May I cut feeding the fish back to around 10% of what they got previously. I am feeding 3 times a week now. The result of this is that the koi is keeping the ponds very clean and when the algae started appearing in early June it was only in the two stream beds.
A friend of mine is a Marine biologist and I asked him about my drastic feeding reduction and he told me that it good to starve the fish during winter. According to him it allows the fish to work off their fat layers and trim them out for the Spring. He reckons that if you do not trim them out in winter you get a situation where the seasonal fat layers start building up in the fish and this is apparently the reason for so many fatalities in female koi when they are around 3 years old. I don't know how much is true but it does make sense and the truth is that the species in my ponds are not feeding aggressively in winter time when in the wild.
In mid June we had a severe cold spell and that killed the 3 oscars and fair number of the mollies and platies. It was expected but deep down I hoped they would survive. I really grew fond of those three oscars
... they had some real attitude.
Now the current status is that since December I did not add any chemicals to my ponds and I also did not test the water this year. The plants looks good, the fish is well with no visible ailments and I feel things are fine. I will add some salt this coming week because it will curtail the string algae in the streams and I do have a few fish that flashes from time to time. I will not add too much salt because the plants really suffer if you push the salt too high.
Interesting is that all the hyacinths died off in my ponds.
As I sit here tonight I am of the opinion that I have achieved my goal of establishing a koi garden and that my ponds have matured into a well balanced and healthy eco system. My koi are between 170 and 300mm now. The bulk is in the range of 250mm with a few smaller ones and a few bigger ones. I am happy with their growth. If I fed them more aggressively I am sure they could have been bigger but I do tend to be quite sceptic of overfeeding any animal.
Here are two pictures.
I will post another contribution on more details of the ponds as well as the spinoffs around the ponds. I planted strawberries, mixed birdseed and sweet potatoes. The latter was done to assist in getting the soil ready for next season as well as priding rapid ground cover.
Thanks again to all that contributed here and I am happy to say that I think that I have achieved basically all of my initial goals.
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