Safe Materials
Aquarium-grade resin, ceramic, glass, silicone-sealed wood/rock, aquarium-grade plastic.
Always from aquarium brands — hobby-grade ensures inertness and safety.
Unsafe Materials
Terracotta (can leach dyes unless Italian-made), painted decor (chips into water), copper-based decor (toxic).
Avoid metal decorations except stainless steel in specific applications.
Sharp Edges
Inspect all decor for rough edges that can tear fins. File down with sandpaper or aquarium sealant.
Especially important for delicate fin fish: bettas, guppies, fancy goldfish.
Hollow Decorations
Ensure hollow pieces have entrance and exit — no dead-end traps.
Small fish sometimes swim into hollow caves and can't turn around. Check size compatibility.