Make Caviar when a Sturgeon pond produces nothing
For the direct pond-to-jar route you need Sturgeon Roe. Normal Roe from another species makes a different product. Start with the correct fish and keep the pond intact while waiting for the bucket.
Catch the parent fish and reserve it
Take a non-training fishing rod to the Mountain Lake outside the Mines in summer or winter, between 6am and 7pm. Rain is not required. Keep a Sturgeon for stocking rather than donating your only catch to the Lake Fish Bundle. Take it to the prepared fish pond and check that the pond interface names Sturgeon. If the pond still names an old species, clearing only its residents with a rod did not reset the pond.
Increase the bucket’s odds
The first Sturgeon occupies a one-fish capacity. It can produce Roe there, but many mornings have no output. Look at the bucket separately from the resident count. The first capacity request asks for a Diamond; deliver one and allow time for the population to increase. Its reproduction interval is four days. At the later seven-to-ten capacity gate, reserve a Nautilus Shell, the beach forage, rather than the Nautilus Fossil artifact.
Use the roe label to choose what goes in the jar
Collect the output and check the species in its name. Put Sturgeon Roe into an empty Preserves Jar. Leave the jar processing until its ready bubble appears, then collect Caviar. Other roe yields Aged Roe; putting a different jar product into a second jar cannot convert it into Caviar. If you are working on the abandoned JojaMart, put the finished Caviar aside and check how many other Missing Bundle options you still need.