Fish Sulfa Forte (Fix Sulfa) SMZ/TMP 960mg Fish Antibacterial

Description

Fix Sulfa – Sulfamethoxazole / Trimethoprim (SMZ/TMP) for aquarium fish

Fix Sulfa by Aqua Soma Labs contains sulfamethoxazole / trimethoprim (smz/tmp) and is labeled for treating a broad range of bacterial infections in ornamental freshwater and saltwater fish.

Available as: 960-mg (30 Count), 960-mg (60 Count).

Before you treat

• Follow the dosing directions printed on the bottle label.
• Treat in a separate hospital or quarantine tank where possible.
• Remove activated carbon from the filter during treatment and keep up regular water changes.
• Complete the full course, even if fish look better sooner.

For ornamental aquarium fish only. Use in pet birds only under a veterinarian’s direction. Not for human use and not for food-producing animals. Keep out of reach of children.

More fish & bird treatments

• Fix Mox (Amoxicillin)
• Fix Flox (Ciprofloxacin)
• Fix Cin (Clindamycin)
• Fix Doxy (Doxycycline)
• Fix Flex (Cephalexin)
• Fix Pen (Penicillin)
• Fix Zithro (Azithromycin)
• Fix Zole (Metronidazole)

Browse all fish & bird treatments · Shipping policy · Refund policy

Fix Sulfa questions

What is Fix Sulfa used for?

Fix Sulfa contains sulfamethoxazole/trimethoprim (SMZ/TMP). Its label lists it for a broad range of bacterial infections in ornamental freshwater and saltwater aquarium fish.

How do I know my fish needs an antibiotic?

Test the water first (ammonia, nitrite, nitrate and temperature): many symptoms come from water quality, parasites or fungus rather than bacteria. Our guide How to choose an aquarium antibiotic explains the signs.

How do I use it?

Follow the dosing directions on the product label. Treat in a separate hospital tank where possible, remove activated carbon from the filter during treatment, and finish the full course.

Can I combine it with other medications?

Don’t combine different antibiotics or other medications in the same tank unless the product labels or an aquatic veterinarian say it’s safe.

Can people or food animals use it?

No. It is sold for ornamental aquarium fish only. It is not for human use and not for fish or animals raised for food.

Last reviewed: November 2026