The fishy arrival means the trout fishing season at the 120 acre site, which is owned and operated by South East Water, is well underway.
In total, more than 11,000 top quality trout will be stocked at the reservoir which is situated at the foot of the South Downs at Berwick, within sight of the Long Man of Wilmington.
Emma Goddard, South East Water's environmental manager, said, "We look forward to the start of our annual trout stocking exercise, as it signals the start of a new season at this wonderful beauty spot.
"The site has a well-deserved reputation for excellent quality fly-fishing with hard fighting, superbly conditioned, great tasting trout."
The fishing season at Arlington runs until June 30 with boat fishing commencing from April 1. Fishing at the reservoir closes in July and August and restarts at the end of September through until December 31.
For those who want to try their hand at fly-fishing, South East Water is again running its popular Beginner's Days, which this year take place on Saturday April 25 and May 9.
Experienced South East Water staff will be on hand to tell you everything you need to know about getting started on this popular sporting pastime and all equipment is provided.
The cost is as little as £10 for 10 to 15-year-olds and £15 for adults, but because of their popularity, booking is essential. An adult and child ticket is also available for £20.
Anyone wishing to fish at Arlington or wanting to book a place on the Beginner's Day should contact South East Water's Fisheries Office on 870810 (ext. 20) or visit www.southeastwater.co.uk for further information.