How to Play Shoal
Shoal is a relaxed aquarium breeding simulation set in a hand-inked naturalist aesthetic. You maintain a small tank of fish, select pairs to breed, and discover new trait combinations that fill your specimen journal. The core loop is gentle and deliberate — no reaction inputs, no timers — every action is a conscious choice about which fish to pair and how to spend your Specimen Credits in the Tech Tree.
To breed, click one fish to select it (a highlight ring appears), then click a second fish. Press the Breed button to open a preview panel showing three possible offspring, each rolled separately from the pair's genes. Body, fin and stripe are drawn from a pool holding each parent's value plus two fresh common values, so a parent passes a given trait about a quarter of the time and half of all rolls land on a value taken from neither parent. Colour is a coin flip between the two parents except for a 15% wildcard that picks any of the six bands. Click the offspring you want and confirm to hatch it into the tank. Every breed action ages all fish by one turn and slightly degrades water quality, so feeding and careful age management are part of the rhythm.
New trait combinations unlock journal entries and award Specimen Credits. Common discoveries earn 3 SC, uncommon ones with a rare trait earn 8 SC, and truly rare combinations with two or more index-3 traits award 20 SC. Spend those credits in the Tech Tree — three branches cover genetics (better inheritance odds), habitat (more tank space, slower decay), and trade (sell fish for credits, then import outside bloodlines carrying genes none of your three starting fish have).
Breeding Strategy
- Do not pair methodically at the start — because body, fin and stripe each land on a fresh random common value about half the time, the same two parents throw very different offspring run after run. Breeding your three starters over and over turns up new journal entries just as fast as working through every pairing, and each hatch gives you three candidates to choose from.
- Watch the tank cap, not just the ages — the Breed button switches off the moment the tank is full, and only two things free a slot: selling, and old age. Fish are removed once their age passes 8 breeding turns (10 with the Breeding Pond), and nothing but breeding advances that clock. Starting capacity is six, so buy Extra Tank or Market Access before you fill it rather than after.
- Trade T1 is the cheapest node in the tree — at 8 SC it is within reach after two or three discoveries, and it is the only way to clear a tank slot on demand. Prices are modest: 2 SC for an all-common fish plus 2 for every index-3 trait it carries, doubled once you own Collector Demand. Treat selling as slot management first and income second.
- Rare traits come off the dice, not the parents — body, fin and stripe each get an independent 8% roll for their index-3 option on every hatch, whatever the parents carry, and Genetics G2 lifts that to 15%. G3 adds a separate 25% roll on top, but only for a trait where both parents are already index-3, so it pays to breed two rare carriers of the same kind. Colour is excluded from that roll: gold is index 3 and still counts as a rare trait when the journal pays out, but from common stock the only route to it is the 15% wildcard landing on gold — roughly one hatch in forty.
- Water quality is a readout, not a gate — every breed knocks 4 points off it (2.8 once Filtration is fitted), and the Feed button spends 20 food to put 25 back. No action in the game is blocked by the number: fish stay breed-eligible at any quality, and the only visible consequence of letting it slide is a browner tint over the tank. Put early credits into capacity and trade instead.
About the Naturalist Aesthetic
Shoal draws on the tradition of 18th and 19th century naturalist field journals — the ink-and-wash specimen plates of artists like John James Audubon and scientific illustrators who documented new species with hand-drawn portraits and precise Latin labels. The aquarium view renders fish as ink-outlined watercolour shapes with sepia borders and aged-parchment background. The journal panel mirrors a field notebook, with each discovered species rendered as a small specimen portrait beside a serif field-journal label. Unlike aquarium simulators that rely on photography or 3D assets, every fish in Shoal is drawn procedurally from its four trait genes — body outline, fin shape, stripe overlay and colour wash composited on the fly — so all 384 combinations are real drawings rather than entries in a sprite sheet.
Frequently Asked Questions
How do I breed fish in Shoal?
Click one fish to select it, then click a second fish to complete your breeding pair. Once two fish are ringed, press the Breed button. A preview panel shows three possible offspring — click the one you want and press Hatch. Each candidate is rolled separately: body, fin and stripe come from a pool of the two parents' values plus two fresh common values, colour is a coin flip between the parents apart from a 15% wildcard draw, and every trait also gets its own low-probability roll for the rare option.
What are Specimen Credits used for in Shoal?
Specimen Credits (SC) come from your journal: the first time a trait combination is hatched it pays 3 SC, or 8 SC if the fish carries one index-3 trait, or 20 SC if it carries two or more. Repeat combinations pay nothing. Once Trade T1 is unlocked, selling a fish also pays — 2 SC plus 2 for each index-3 trait it carries, doubled if you own Collector Demand. You spend credits in the Tech Tree to unlock genetics upgrades, habitat expansions, and trade options.
What is the Tech Tree in Shoal?
The Tech Tree has three branches of four nodes each, all bought with Specimen Credits. Genetics improves the odds of hatching the rare index-3 traits. Habitat expands tank capacity from 6 to 9, then 12, then 18 fish, slows water-quality decay by 30%, sets a quality floor of 20% and adds two turns to the maximum age. Trade first unlocks selling fish for credits, then imports two outside-bloodline fish, then a specimen carrying two rare traits, and finally doubles your sale prices.
How many species combinations are there in Shoal?
Shoal has 384 unique trait combinations — four body shapes × four fin types × four stripe patterns × six colour bands. Discovering all 384 is the long-term goal. The index-3 option in body, fin and stripe is the rare one: each gets its own independent 8% roll on every hatch regardless of what the parents carry, and Genetics G2 (Recessive Lift) raises that to 15%. Genetics G3 adds a separate 25% roll for any trait where both parents are already index-3.
What happens if I neglect the tank in Shoal?
Water quality falls 4 points with every breed, and the Feed button spends 20 food to restore 25, so a neglected tank slowly tints brown. That tint is the whole consequence — no action in Shoal is gated on water quality, and fish stay breed-eligible at any level. The Habitat branch softens the decay anyway: Filtration cuts it by 30% and Oxygenator sets a floor of 20% that quality cannot fall below.
Do fish die in Shoal?
Yes — each breed action ages every fish in the tank by one turn, and a fish is removed once its age passes 8 turns. Breeding is the only thing that advances that clock, so a tank you leave alone never changes. Habitat H4 (Breeding Pond) raises the limit to 10 turns. Sell fish before they age out (requires the Trade T1 unlock) to recoup Specimen Credits. Balancing the age of your fish is a key part of managing a healthy breeding programme.
Is progress saved in Shoal?
Yes. Shoal saves your tank, journal, credits, and Tech Tree progress automatically after every action and when you leave the tab. All progress is stored locally in your browser. There is no account or login required. Clearing your browser data will erase your save.
