Otocinclus catfish and cherry shrimp share a job description — graze the tank's surfaces, bother nobody — and that is why they combine so well. An oto's mouth is a small sucking disc built for scraping algae film off leaves and glass; it has neither the size nor the inclination to hunt shrimp. Cherry shrimp, for their part, ignore the otos entirely, picking over the same plants centimetres away. In a planted nano tank this pairing reads less like two species stocked together and more like one continuous clean-up crew working in shifts.
A mature tank is the entry requirement
Both animals eat what a tank grows, which means a brand-new aquarium is a food desert for them. Wait until the tank has run for several weeks and developed the invisible biofilm on wood, stone, and glass that shrimp pick at constantly, plus some soft algae growth for the otos. Stability matters as much as food: otos are famously sensitive in their first weeks and do poorly through ammonia wobbles or big parameter swings, and shrimp moult badly in unstable water. Warm water in the mid-seventies Fahrenheit, gentle filtration with a sponge over the intake so shrimplets are not drawn in, and a cycled filter that has already proven itself — that is the platform this pairing stands on.
Groups, grazing, and the supplement schedule
Otocinclus are schooling fish at heart, and a group of six or more grazes boldly across open glass while a pair hides behind the filter. Cherry shrimp colonies start with ten or so and grow from there, with berried females carrying eggs under their tails through the month. Neither species can live on tank growth alone once numbers build, so supplement deliberately: algae wafers broken small, blanched zucchini or spinach weighed down overnight, and shrimp-specific food a few times a week. Remove uneaten vegetables the next morning. A tank that looks spotless is not a success here — it usually means the grazers are hungry, and leaving a back pane of glass uncleaned is a legitimate feeding strategy.
Watching the pairing work — and its limits
The honest caveat is newborn shrimplets: they are speck-sized for their first days, and while otos do not hunt them, dense moss and plant cover are what carry a baby shrimp through that window, so plant thickly if a growing colony is your goal. Adult and juvenile shrimp are entirely safe. Keep copper-based medications out of this tank, since copper is lethal to shrimp, and treat any plan for new fish with suspicion — the moment a larger mouth arrives, the shrimp half of this arrangement is at risk. Otos that arrive thin from the shop need food immediately, not a dirty tank to clean; a fat, round belly on a resting oto is the sign the system is working.
Small duties, shared properly
A grazing tank's care is a list of small, easy-to-skip jobs — drop the wafer, swap the zucchini, top up the evaporated water — and small jobs are the ones that fall through when only one person holds them in their head. Listing those duties in KinsLe's Care Teams, where each completed task is marked with its time, means the otos get their supplement even on the weeks their owner is travelling, and the shrimp colony's routine survives the handover intact.