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If we are talking about a 12"-15" LSN catfish, then it is either a fully grown Sorubim elongatus (max ~1') or a growing true Sorubim lima (max ~2'). Either one will gulp or attempt to gulp down your fire eel and possibly will try to eat the red tail shark, perhaps not at 12" but at 15" much more likely.
They are 100% predators, not scavengers in the wild and will always prefer live foods even if trained to take non-live. Whatever fits in their deceptively narrow (because it is collapsible) mouth, will most likely be eaten sooner or later.
If we are talking about a 12"-15" LSN catfish, then it is either a fully grown Sorubim elongatus (max ~1') or a growing true Sorubim lima (max ~2'). Either one will gulp or attempt to gulp down your fire eel and possibly will try to eat the red tail shark, perhaps not at 12" but at 15" much more likely.
They are 100% predators, not scavengers in the wild and will always prefer live foods even if trained to take non-live. Whatever fits in their deceptively narrow (because it is collapsible) mouth, will most likely be eaten sooner or later.