Freshwater Sponge (Ephydatia muelleri)

Ephydatia muelleri is a freshwater sponge that is difficult to maintain over long periods of time. They perform best in fully cycled freshwater systems with stable conditions. Small aquaria or large containers with gentle, continuous water movement are sufficient, as constant flow is required for feeding. They are obligate filter feeders and rely on suspended particles rather than direct feeding. Cultured algae and fine particulate foods can be spot fed several times per week. Tetraselmis chuii and Nannochloropsis sp. are suitable primary feeds, with Escherichia coli and Saccharomyces cerevisiae commonly used as well. Overfeeding should be avoided, as water quality degrades rapidly in small systems. They readily attach to glass or stone substrates and spread slowly under stable conditions. Light is required to support their symbiotic algae. Under unfavorable conditions, they may produce gemmules, which can persist through cold or low nutrient availability and regrow once conditions improve. Gemmules can be stored at 4 °C and remain viable for at least one year.