Offering a ray of hope in the struggle to save a tiny fish enmeshed in California’s water disputes, state officials say they have found a way to move around river water to produce more food for hungry or starving Delta smelt. The endangered fish, at record low numbers, has been hurt by a long-term decline in tiny water plants and creatures at the base of the food chain in the Sacramento-San Joaquin River Delta, a source of water for 25 million Californians.