Pulling more than 20A from a SLA was never a good idea. SLA were never intended for high currents for more than a few seconds. OK starting a car, no use for running it. Pulling continuous high current shortens the battery life enormously, NiMH is much lighter for the same power storage and can support high currents. Much easier to look after than Lithium as well. SLA only got used in the past because they were the only game in town.
The ESC should have its own current limiting (but I'm not familiar with that particular one), trying a 30A fuse should be safe.
It might be a good idea to check that everything turns freely, and that there is not too much prop. Over-propping is a major cause of causing electric motors to pull too much current.