Bacteria & water moulds
Bacterial infections: identify the cause
A bacterial finding needs context. Environmental stress and damaged tissue can allow infection to become established.
What the vet may investigate
Aeromonas, Pseudomonas and other bacteria can be involved in fish disease. Culture and susceptibility testing may help choose treatment; redness alone cannot name the bacterium.
Why the environment matters
Record water readings, recent handling and organic waste. Improving the visible sore without correcting the cause can leave the fish vulnerable.
Use antibiotics properly
Do not use leftover human or pet antibiotics. A fish vet should decide whether antibiotics are appropriate and how they should be given.
Sources & further reading
Original WakeyKoi wording, informed by the references below. Linked clinical resources explain the evidence and their scope; they have not reviewed or endorsed this website.
Related guides
Educational guidance cannot diagnose an individual fish. Breathing distress, severe injury or unexplained losses need prompt professional assessment.