Kesh Aquatics in Immingham, Lincolnshire, has been the victim of two break-ins in one night, reports the Grimsby Telegraph.
The break-ins, which occurred at 6.25pm on Saturday evening, and 1.25am on Sunday morning, are currently being investigated by the police.
The thieves, who are also believed to have targeted a storage container next to the supplier, made their way in by smashing their way through the side entrance doors.
Cash was taken from the till, along with some aquarium lighting systems. The shop also deals in reptiles " and from here tarantulas, an infant boa constrictor and milk snake, along with reptile food, were stolen.
However, shop owner Kev Howell believes that the most valuable item the thieves stole was actually his computers hard drive " which would only be "worth about 10 to sell on to somebody."
Mr Howell had been working on a project for the Blue Planet Aquarium, designing new aquarium systems for the public aquarium. The prototypes of the systems were tested using the facilities available in his shop and workshop.
Unfortunately, the designs for these aquarium systems were held on the stolen hard drive.
"To me, it's the equivalent of losing 20,000", he told the Grimsby telegraph. "I've spent so much time working on new systems for the centre. Losing all that is just devastating."
Further damaged was caused when "whether by accident or not they switched off the computerised water controls to a fish tank, flooding the shop."
Anyone with information should contact the police on 0845 60 60 222, quoting case number 839.