Stone fish
Cod-line fish that turn a stone block into a steady supply of that stone, and never copy themselves.
Stone fish are the simplest resource fish: bred from a pair of 
Raw Cod and a block of stone, they yield that same stone, in bulk, every time they breed. They are a way to farm building stone with fish instead of a quarry.
The fish#
| Fish | Catalyst | Yield per breeding |
|---|---|---|
 Andesite Anchovy |  Andesite | 8 Andesite |
 Calcite Cisco |  Calcite | 8 Calcite |
 Cobble Sculpin |  Cobblestone | 8 Cobblestone |
 Deepslate Dab |  Cobbled Deepslate | 8 Cobbled Deepslate |
 Diorite Dory |  Diorite | 8 Diorite |
 Granite Grunt |  Granite | 8 Granite |
 Tuff Tuna |  Tuff | 8 Tuff |
Making one#
Put two cod in a Spawning Basin with fish food and the stone in the catalyst slot. Unlike other mutations, this one is certain: each breeding rolls a 100% chance, so every breeding gives a new stone fish and uses up one stone.
Spawning BasinYou need two of the same stone fish to farm it, so that is two breedings and two stone blocks. Switch the catalyst to change the species: the cod stay the same. The breeding page covers the mechanics in full.
Farming them#
Put a pair in a row of an Ecotone. Every breeding gives 8 of the fish's stone, with a 100% chance, into the row's resource output. At the base tier that is one load every 10 s per row, and all 4 rows together give 32 stone per breeding if you fill them.
Stone fish never copy themselves: their chance to make another fish is 0%, in the Ecotone and in the Basin. The pair you start with is the pair you keep, which is fine, since breeding never uses a pair up. For more stone, make more pairs.
- The resource output is one slot per row, and it fills fast at this rate. Anything that does not fit is lost, so pipe it out through a port with auto-output, or fit a
Void Module to throw away what you do not want. - An Infusion Module, Fish Meal and Prized parents all double yields the usual way; see Prized fish.
- Do not grind them. A Triturator turns a stone fish into just 1 of its stone and a Fish Meal. They are worth far more in an Ecotone.
Every stone fish cooks into food like any other fish. The full list of species, including these, is on the species page.