40
10 gallon fish tank filter cartridges
Skip itBrand-locked demand (top 5 brands take 94% of clicks) — this niche doesn't clear our bar today.
Conversion
Incredible13.7%search→purchase rate — share of searches ending in a sale
Returns
Great1.9%return rate — above 6% kills the launch gate
Avg price
Good$14.29avg listing price — sweet spot $15–$100
Price range
Okay$6.37–$22.54cheapest to priciest tracked listing — scored on the share inside $15–$100
Quality gap
Okay4.5★avg incumbent rating — lower means beatable quality
Growth
Okay+3.2%90-day search growth — must beat 0% to launch
Market size
Okay$104K$104K/yr · 53K searches
Review moat
Bad12,594.42avg incumbent reviews — the moat a new listing must climb
Competition
Bad77%top-5 click share — a locked-up shelf
Brand share
Bad94%top-5 brand share — brand-locked demand