Koi Pond Keeper

Koi fishing, raising & pond-building minigames for RPG Maker MZ

Dig a pond. Cycle the filter. Land a 65 cm Showa without snapping your line. Sedate a sick koi, find the parasite under the microscope and pull out an anchor worm with tweezers.

Koi Pond Keeper brings Surgeon Simulator-style, hands-on minigames to RPG Maker MZ, built on real koi-keeping knowledge. It's one plugin file, drawn entirely in code: no images, no audio files and no other plugins needed.

6 hands-on minigames

Pond Architect. Design a pond with a live inspector that rates volume, depth, turnover, filtration, UV-C, aeration, liner and heron safety. Then build it by hand: find buried cables, dig to depth, level the rim, clear stones, smooth the liner, plumb the filter loop, dechlorinate, and decide when the koi can go in.

Water Lab. Fill the tube to exactly 5 mL, count your drops, shake, wait, match the colour chart and titrate KH. Diagnose new pond syndrome, nitrite poisoning, a pH crash, low oxygen, chlorine or green water, calculate the dose, and see the result 48 hours later.

Feeding Time. Choose the right food for the water temperature (or don't feed at all in winter), follow the 5-minute rule, make sure the shy fish eat, and net out the leftovers.

Koi Fishing. Pick bait, hook, line and drag. Cast, wait for the float to go under, and strike. Then play the fish on a tension gauge, net it head-first, unhook it on a wet mat and release it upright. You're scored on fish welfare, not size.

Koi Clinic. Spot the sick koi and herd it gently into a bowl. Mix and buffer the sedation bath, lift at stage 3, keep the gills wet, take a skin scrape and identify parasites under the microscope. Then treat it by hand: clean an ulcer, dab on iodine, seal the wound or remove an anchor worm.

Show Judge. Name 15 varieties from above, spot the faults, and rank a show bowl the way real judges do: body first, then skin quality, then pattern.

Plus a living pond

My Koi Pond is the player's own pond, simulated day by day:

• the nitrogen cycle, KH and pH, dawn oxygen, algae and UV
• seasons you can see: cherry petals, dragonflies, autumn leaves, snow and ice
• random events: heatwaves, thunderstorms, power cuts and cold snaps
• growth, disease, herons and 3-week quarantine
• a 90-day Water History chart, plus growth milestones and birthdays in the pond diary

Keeper Badges: 18 achievements, with personal bests on every cabinet card.
Keeper's Handbook: reference pages for every topic, variety, disease and microscope slide.

Made for developers

• One cabinet, one command: Plugin Command → Open Menu. That's it.
• Results to your variables: score (0–100), grade (S–D) and a pass switch, set globally or per command. The event waits until the minigame closes.
• Common event after any minigame, plus a koi-count and badge-count variable.
• Story tools: Build Pond Now, Add Koi, Advance Days, Set Day of Year and Get Pond Stats.
• Script API and hooks: KoiPK.open(), KoiPK.addKoi(), KoiPK.on("finish" / "badge" / "day" / "event") and KoiPK.registerBadge().
• Extend it: add your own water cases, handbook pages and badges from a small plugin below this one.
• Translate it: shared labels live in one KoiPK.TEXT table.
• Easy / Normal / Hard, metric, imperial or both, and four climates.
• Mouse, keyboard, touch and gamepad. Optional colour assist for colour-blind players.
• Saves automatically with the game, and older saves upgrade on their own.

Realistic and informative

The figures follow common koi-keeping and aquatic-vet guidance: ammonia and nitrite at 0, KH 5–8 dKH, roughly 1,000 L per adult koi, no feeding below about 10 °C, and MS-222 at about 100 mg/L buffered with bicarbonate. Every lesson appears on the results screen and in the Handbook. Doses are teaching examples. Real keepers should follow product labels and an aquatic vet.

Install

1. Copy Koi_PondKeeper.js into js/plugins.
2. Add it in the Plugin Manager and turn it ON.
3. Make an event: Plugin Command → Koi_PondKeeper → Open Menu.

Requirements

• RPG Maker MZ
• 816×624 or larger (centred on bigger screens)
• No other plugins, images or audio

Terms of use

• Use it in commercial and non-commercial RPG Maker MZ projects.
• Credit appreciated: "Koi Pond Keeper by RPG Maker Plugins".
• Don't resell or redistribute the plugin file itself.

Grab it and give your players a pond worth keeping ▶