Reproductive ageing is intrinsically linked with the interactions between the germline and the soma, where germline maintenance appears to come at the cost of somatic ageing. Signalling pathways determine the level of cellular and genome maintenance in the germline and the soma. Because germline maintenance is predicted to be costly, the allocation to germline maintenance may vary throughout an organism’s life resulting from the putative trade-off between somatic maintenance, offspring number and offspring quality through the production of high-quality gametes carrying healthy genomes. Males appear to be particularly vulnerable to sub-optimal germline maintenance and germline ageing as spermatogenesis continues throughout life and involves continuous mitotic and meiotic divisions for tissue proliferation. We tested the germline-soma interactions in male zebrafish Danio rerio using knockdown and knockout to generate germlinefree fish and compare somatic responses to genotoxic stress in germline-free and germline-carrying males. We also performed mutation accumulation experiments using the nematode Caenorhabditis remanei to assess germline mutation rates as an indicator of germline maintenance in young, peak reproductionaged and old worms. All our experiments hint at a tight regulation and interaction between germline and soma and I will discuss our results in the light of the expensive germline hypothesis and its role in reproductive ageing.