A bot with the SHORT algorithm sells the first coin of the trade pair, receiving payment with the second coin of the trade pair. Therefore, for a bot with SHORT algorithm, the deposit (virtual wallet) must be in the first coin of the trade pair.
Consider the BTC-USDT trade pair. Here, the first coin of the trading pair is BTC, the second coin of the trading pair is USDT. The bot will first sell its BTC for USDT when the BTC price increases, after which it will buy all the BTC sold for USDT if the BTC price falls. That is, in order for the bot to start trading (selling BTC), it needs to initially have this BTC and this is the first coin in the trading pair. Therefore, in order to create a bot with the SHORT algorithm in the BTC-USDT trading pair, it is necessary for the bot to have a deposit (virtual wallet) in the BTC.