We compute the linear power spectrum of cosmic string sedeed fluctuations in the context of neutrinos with a strong self-interaction and show that it is very similar to that obtained in the context of `normal' neutrinos. We compare our results with observational data and show that for any value of the cosmological parameters $h$ and $��_0$ the interacting hot dark matter power spectrum requires a large scale dependent biasing parameter.

5 pages, 3ps figures, Latex, uses mn.sty, submitted to MNRAS