- Location
- USA
+5 XP if someone figures out a life cycle for these fish that is plausible according to real science + MfD-onscreen statements, and it makes sense to the QMs. They spawn eggs once per year and the fry are cannibalistic of both eggs and each other. Partial award if we use part of your idea but make changes.
"The koi are doing fine. The junior piscitist turned out to be capable of managing things. If the fish are used for chakra then it will be at least six months before they can breed. They typically breed some time between May and July, meaning that Lord Noburi may draw on them for the next six weeks or so but should refrain after that point. After they have spawned it is safe to tap the adults for another six months, or longer if we don't need them to breed. The spawn take approximately a year to reach sexual maturity, at which point we can either breed them or tap them for chakra. One of the fish sickened and died at the change in environment, so we only have eleven. No more are forthcoming, as we are expected to breed our stock up to forty on our own.
- A school of koi is defined as 1 or more koi each of which is within about 10m of the school's centroid. Each koi in a school…
- ...has a max of N CP, where N is the number of koi in the school
- ...requires about M kg of food per day, where M is the maximum number of CP that koi had that day. This is intended only as a guideline; the QMs aren't going to track it precisely.
- The koi have a raiton attack (which may or may not be the same as an electricity attack). It is AOE spherical and targets Physique. Fish in larger schools have stronger attacks. Koi are immune to this attack.
- Koi will usually issue a warning zap whenever a non-koi approaches, although they generally don't put much oomph into it unless they are hungry, angry, or frightened.
- They take 8-10 hours to fully regenerate their chakra.
- Moving into a school raises their maximum CP, not their current CP.
- When koi move apart after spending chakra or being drained of it, they can end up dead. It's unclear the exact mechanism, but presumably it has something to do with their maximum CP dropping (and therefore their current CP dropping) while the effect of the spend/drain is still applied and they end up drained below 0 CP.
- Yes, they are dumb enough to kill themselves like that
- Koi will happily eat themselves to death, so feedings must be spaced out over the course of the day in order to give them time to digest.
- As a very rough rule of thumb, a koi pond should be 5,000 liters (1,250 gallons) per fish. There's 1,000 L per cubic meter. Depth doesn't help much as they generally stay at the surface and rarely dive more than a meter. (These are for chakra koi in MfD; don't use this as real-life data.)
The Wakahisa give:
- [...]
- 25 koi fish.
- Wakahisa aquaculture experts to come to the Gōketsu estate and direct the process of setting up an appropriate koi pond. All expenses will be borne by the Gōketsu.
- An ongoing Wakahisa aquaculturist presence (2-3 experts, plus a couple of bodyguards and some civilian staff. These people will be rotated periodically) in dedicated housing at the Gōketsu estate. These experts will be responsible for all care and feeding of the fish.
- [...]
- All fish-related expertise will be kept concealed and remain the intellectual property of the Wakahisa clan except for the minimum necessary to allow the Gōketsu to make safe use of the fish. The experts will be allowed to take reasonable precautions to ensure this, so long as it does not endanger any Gōketsu.
"Ordinarily, breeding season would already be upon us, but I have been delaying it while we were on the road by restricting the amount of food I give them, and also through use of some additives in their water. We can only do that for another week at the very most and then the fish must be allowed to breed or they will sicken.
"Once their season begins, the fish will mate repeatedly, but they will not be fertile unless conditions are correct—the amount of available space, an assured food supply, proper temperature and water flavorings, and various other factors that are secret to my arts. Assuming a productive match, each female will spawn up to a thousand eggs, of which perhaps half will actually bear fruit. The firstborn young will emerge ravenous and will preferentially eat the other eggs unless they are immediately transferred to a separate nursery. Even under optimal conditions, most of the young will die within a few days or a week. Any fishling that makes it for a month will probably make it to adulthood."
"And therefore we should expect...?"
"Oh! Yes, sorry sir. Under the care of a master piscitist it would be reasonable to expect perhaps twenty fishlings from each pair to make it to one month. If they live that long then the amount of care required drops tremendously and they will generally make it to adulthood unless something goes greatly wrong."
"Let me clarify the question," Hazō said quickly, eager to head off the string of caveats and equivocations that he saw looming. "I want to hear a specific number of months after birth that you would feel comfortable draining chakra from a koi for your own use assuming that you wanted to do so in a sustainable way that would not hurt the fish."
"Um...well... An adult koi—that is, a one-year-old—can have chakra drained from it every day without suffering any damage. Unfortunately, having their chakra levels fluctuate too much will delay or eliminate the fish's breeding cycle for the year, so we typically divide the fish by purpose—one set of pools for the breeders and one for the suppliers."
Wakahisa bent and dipped his hand into the flowing stream that cut through the north end of the Gōketsu estate. "This water is far too cold, sir. To be comfortable, koi want a temperature approximately that of a cool summer day. It needs to be slightly warmer for them to breed, so there will need to be a graduated series of pools." He shook his head in disbelief. "Lady Sadaharu truly never arrived?"
One moment, please...
pondinformer.com
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How Often Do Koi Fish Lay Eggs? Reproduction, Breeding, & Care
How often do koi fish lay eggs? The answer along with details regarding koi fish reproduction and fry care is reviewed in this guide.
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All the fluff in the story so far seems pretty reasonable. The main difference, I think is:
Real life koi:
- Spawn in hundreds of thousands or more
- Take 3-4 years to reach sexual maturity
- Spawn in thousands at once
- Take 1 year to reach maturity for chakra drain (though not necessarily sexual maturity?)
- The fish arrived at the end of July. Despite what the piscist said, the spawning failed and we didn't get any new koi while we were setting up the pond.
- Due to the stress of moving, or due to the piscist being a junior.
- Either way, we have only 11 healthy fish.
- Come June, the koi will spawn thousands of eggs.
- The main limiter here is cannibalism.
- Surplus food and the presence of the piscist means that keeping the few dozen fry we need alive is easy.
- The fry have been transferred to one or more smaller water areas.
- With twenty fishlings per pair making it to a month, and probably 18 of that making it to adulthood, we should expect that we will fill our pond in a single generation.
- There will be over 40 fry, but the piscist will cull the numbers down.
- They probably have some intuition for how many fry die ordinarily, and will calibrate it so that the final number of fish that can supply chakra equals 40.
- If they instead immediately cull the numbers down to 40 after the first month, with a reasonable 10% attrition on the young ones, we should still expect to end up at 37.
- The actual number of fish we will actually have available is less than 40. Concretely, we will have 32 koi producing chakra, 4 reserved for breeding, 2 immature and 2 dead to be replaced in the next year. (total guesses)
- Some fish die or fall ill. Generally, we will want to reserve at least two fish for half the year for breeding, if only to produce one or two extra koi per year to cover the yearly attrition loss.
- A breeding pair should probably be kept in a separate pond at all times in order to not keep all our eggs in one basket. Maybe even two.
- That also means that there may be a couple koi growing up. If these young koi don't count against our 40 cap, we should be fine.
- Eventually, older koi need to be culled to keep a diverse age range in the pack, so that there are always koi at an appropriate age for spawning. In general, there will always be some number of koi that are immature.
- 32 is a good stable number, accounting for immature koi, dead koi, or breeding pairs.
- In general, we should expect to be able to draw 3000-3500 CP per day from the pond.
- With almost all the total koi we need accounted for, not all the fish need to be reserved for spawning. Once they spawn, 7 out of 11 koi can be repurposed to chakra production full-time, while the 4 remaining (two breeding pairs) will be removed in 6 months.
- So in terms of when we have chakra available:
- Now - June:
- 0 koi tappable
- No chakra from pond.
- June - December:
- 11 koi tappable
- 320 CP per day
- December - next June:
- 7 koi tappable
- 130 CP per day
- All future June - December:
- 36-40 koi tappable
- ~3400-4200 CP per day
- All future December - June:
- 32-36 koi tappable
- ~2700-3400 CP per day
- Now - June: