The residents see an intruder, not a guest
Your established community runs on settled agreements: this corner belongs to the catfish, the surface belongs to the hatchets, the pecking order at feeding was decided months ago. A large, confident newcomer is exactly the kind of event those agreements were not written for, and the residents' first responses — flaring, following, investigative nips — are them testing whether the stranger changes the map. The newcomer, meanwhile, is stressed from transport and has no hiding place memorized. Your job is to soften both sides of that first meeting.
Quarantine and homework come first
Keep the centrepiece fish in a separate quarantine tank for a couple of weeks before it meets the community at all. That protects your established fish from anything the newcomer is carrying — centrepiece fish are often wild-caught or shop-kept in crowded systems — and it lets you confirm the fish is feeding confidently and behaving normally before it has to compete for food. Use the time honestly: check the adult size and temperament against your actual stock, not the stock you plan someday, and confirm your water suits the species. A centrepiece that quarantines well but is wrong for the community should be returned, not introduced hopefully.
Introduction night, step by step
Feed the residents a good meal first — hungry fish meet a stranger as competition, fed fish meet it as gossip. Then rearrange two or three pieces of decor and shift the plants slightly; this blurs the exact boundaries residents defend, so the newcomer is not the only change in the tank. Float the bag or drip-acclimate to match temperature and chemistry, dim or switch off the tank lights, and release the fish gently near cover rather than in open water. Leave the lights low for the rest of the evening. The first meeting happening in near-dark, among re-scrambled landmarks, with full stomachs, is the calmest version of it you can arrange.
The first days of diplomacy
Watch feeding first: the newcomer must actually eat, so drop some food near where it shelters while the residents feed at their usual station. Short chases that end when the newcomer retreats are negotiation; relentless pursuit, cornering, torn fins or a newcomer that has not eaten in several days is a failed introduction — separate them, rest the newcomer in quarantine, and decide whether different stocking or a return is kinder than a second attempt. Check the newcomer each morning for spots, fungus or clamped fins, since introduction stress can let a latent illness surface; visible disease or a fish weakening day by day is the point to isolate it again and contact an aquatics-savvy veterinarian.
A record that starts on day one
A centrepiece fish becomes a long-term resident, and its file starts with this fortnight: where it came from, its quarantine history, what it ate, how the introduction went and any treatment the vet advised — KinsLe's Pet Passport keeps that history in one portable packet with the fish's profile, ready for vet visits, a future handover or simply reminding you next year how this fish's story in your tank began.