if you are calling it a hobby and not a business, that you can deduct related expenses only up to the amount that you took in from the hobby. For example, if you produced a couple of clutches of babies and sold them for a total of $2,000, then you could deduct up to $2,000 in expenses (food, mileage required to get food or other supplies or for sales, pro-rated electricity for the snake room, advertising, professional dues, etc). But that a hobby can't deduct more than you took in.
If it is a business, the IRS will allow you to actually lose money and show a loss that can be deducted from other income (such as a regular job), at least FOR A WHILE. I think that the rule of thumb is that you need to show a profit within 3 or 5 years, or something similar. But there are always exceptions. But deducting losses beyond income is for a business, not a hobby.
I am not an accountant - my CPA does my taxes. But that is my unprofessional gleaning of tax info over the years. The details are complicated, so don't rely on any nonprofessional (such as me, lol!) to be the last word. Even CPAs and IRS agents themselves often can't seem to agree with the final word. So you can find general ideas of how it works here, but do careful research, and rely on professionals for the details.