SpawnOS
Breeding records for fish
Free · Designed for iPad. Not verified for macOS.
Log one spawn date and SpawnOS builds the timeline. Every breeding record is free, with no cap on projects. Pro adds unlimited Ask SpawnOS; Free includes 10 a day.
SpawnOS keeps your breeding records in one place and tells you what should be happening in the tank today.
Spawn dates in a camera roll. Milestones in your head. A lineage spreadsheet you stopped updating three spawns ago. SpawnOS replaces all of it.
YOUR FIRST BREEDING PROJECT IS FREE
Register your animals, build a pair, record a spawn and follow the entire timeline through to grow-out without paying anything.
REGISTER YOUR FISH
Name them, record species, sex, visible traits and photos. Your stock list stops living in your head.
BUILD A PAIR
Pick two parents. SpawnOS checks species and sex, shows what tends to appear in the fry based on the traits you recorded, and warns you if the two fish are related.
RECORD ONE DATE
Log the spawn and SpawnOS builds the rest - hatch, free-swimming, when to pull the male, first feeding, the move to baby brine shrimp, water changes, grow-out and jarring. Each stage carries the window it should fall in and what to watch for.
IT ADAPTS TO YOUR TANK
Confirm what actually happened and the remaining timeline shifts to match. A spawn that hatches late does not leave you with a schedule that is wrong for six weeks.
KEEP THE LINEAGE
Register offspring against a spawn and SpawnOS links the generations for you, so relatedness warnings get sharper as your lines grow.
ASK SPAWNOS
A breeding assistant that knows which pair you are asking about, what stage the spawn is at, and what the species profile says.
PREPARE AHEAD
Prep checklists and reminders surface before a stage begins - including the one that costs people whole spawns, having first-food cultures running before the fry need them.
WHAT SPAWNOS KNOWS, AND WHAT IT DOESN'T
Betta splendens and guppies have SpawnOS-verified breeding timelines with reviewed milestone windows. Other species - mollies, platies, Neocaridina shrimp, corydoras, angelfish, clownfish and more - register and track today, and SpawnOS can research a species profile on request. Where its confidence is lower it says so, instead of borrowing another species' biology and giving you dates that are confidently wrong.
Trait predictions read the visible traits you record on both parents. SpawnOS does not know your fish's genotype and does not claim to - betta marble and koi patterning in particular are flagged as unstable rather than predicted.
SYNCED AND YOURS
Records, photos and reminders sync to your SpawnOS account and restore on a new device. Your data is private to your account on every plan, and nothing you have recorded is ever locked or deleted because of a plan change.
SPAWNOS PRO
Free covers one active breeding project. Pro is for running several at once, with one history across all of them.
Built by Blackwater Aquatics Canada - live foods, shrimp and betta specialists.
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The developer, jaeden doody, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
- Contact Info
- User Content
- Identifiers
Accessibility
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Information
- Seller
- jaeden doody
- Size
- 4.3 MB
- Category
- Lifestyle
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Blackwater Aquatics Canada