Having been on both sides of the fence, here are some things to keep in mind when considering that you're a "private breeder" vs. a typical lifestock supplier.
Cash Flow - a lot of LFS work with a budget, usually pretty tight. The sometimes have to meet minimum orders with livestock suppliers, or at the very least, they know how much they have to spend to make an order worthwhile. As a private breeder, you're trying to gain access to a portion of that budget. Buying $100 or $200 from you may force the LFS to postpone a typical standing order, or put them in a lesser discount level etc.
Quantities and Selection - Unfortunately, it's not like they can get EVERYTHING they need from 1 private individual. Most shops don't want 20, 30, 50 or more of any one thing...they may really want 3 to 6 at a time, delivered as needed. As a private breeder, you can't provide that. Show up with 25 Ocellaris and you're gonna have to take a bite on the price.
Timing - how many private breeders can make a delivery run on a weekday, i.e. 11:00 AM, or 2:00 PM. The last thing a LFS manager wants to do is be putting fish away at 6:30 PM in the evening when his shop is most likely to be full of customers.
Your "Quality" as a "business - let's face it, if you're just some guy walking in off the street peddling fish, NO ONE is going to take you seriously and pay you serious cash. Most LFS look at a private breeder and feel they are doing YOU a FAVOR by taking your EXTRA fish off your hands. You're gonna get beat up on price there too.
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Solutions - there are some things you can do to make yourself more marketable.
Become a real business - yes, letterhead, logo, business cards etc. There are also tax considerations that may or may not be beneficial to you. I.e. for a while I turned my Orchid Hobby into a small Orchid Breeding Business - our first year we had sales approaching 30K, but when tax time came and all the expenditures were laid out, actual profits according to the IRS tallied up to around $500. I must say I never sold so many baby orchids, but on the flipside the amount of effort I put in hardly made the "business" financially viable. But I DIDN'T have ANY problems moving plants and getting a GOOD price and was RESPECTED by my clients. The moral I guess is that you have to find a good balance here, but you have to present yourself as more than just some hobbyist who's gone a bit nuts.
Expand your selection - don't just breed Ocellaris, breed other items that have demand as well. Not sure what those might be, but if a breeder is periodically offering 10 different items, a LFS is much more likely to buy than if you're just the "occelaris" guy.
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Those are my thoughts, having been at literally every side of the industry from Retail to Wholesale to small Hatchery. On the retail side, breeders were a VALUED resource because the quality was USUALLY excellent and the price was VERY VERY LOW.
There's a reason I sat at many a fish auction buying box after box of fish that no one in the "club" was bidding on - I knew full well that the retail value of some of those things was 20X what I was paying.
Bottom line - if you look like a private breeder, act like a private breeder, and sell like a private breeder, you'll get walked all over like a private breeder. So be a professional, be a real business, offer a fair selection and don't give in and sell cheaply - it will take longer but ultimately you'll be a valued source vs. that clownfish guy who brings us cheap occellaris once in a while.
Just my $0.02
MP