This dataset contains fitness-linked life history traits, environmental data, and protein and gene expression data for Daphnia magna. Life history data were measured in common garden experiments. For each clone of the same genotype across all experiments, size at maturity (distance between the head and the base of the tail spine), age at maturity (first time eggs were observed in the brood chamber), fecundity (total number of offspring released summing first and second brood), and mortality were measured. Critical thermal maximum (CTmax) was measured on the experimental animals. Environmental data consisted of Secchi disk depth (water transparency) ; total phosphorous; and total nitrogen for the years 1971–1999; a record of pesticides 1955–2010; temperature records over the past century 80 km from Lake Ring. Organic and carbonate contents of the sediment was estimated using the loss on ignition (LOI) method. Hb protein data consisted of constitutive Hb protein crude content animals reared in normoxic (saturated oxygen level) conditions at two experimental temperatures, 20 and 30°C. Heat shock protein expression was measured in four heat shock proteins (HSP20, HSP60, HSP70 and HSP90). Total RNA, qPCR, mean CT (cycle threshold) value per sample and per protein were collected. Full details about this dataset can be found at https://doi.org/10.5285/13f878dc-ef87-45d5-be8c-5733c88c30e9