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Fish Flex

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Fish Flex (Cephalexin) 250 mg, 100 Capsules
Price: $49.64
Item #: 1013957 -
Availability: In Stock
Fish Flex (Cephalexin) 250 mg, 30 Capsules
Price: $17.06
Item #: 1013956 -
Availability: In Stock
Fish Flex Forte (Cephalexin) - 500 mg 100 Capsules
Price: $49.64
Item #: 1014044 -
Availability: In Stock
Fish Flex Forte (Cephalexin) - 500 mg 30 Capsules
Price: $27.97
Item #: 1014043 -
Availability: In Stock

Products 1-4 of 4

Cephalexin Fish Antibiotics

Fish Flex and Fish Flex Forte are cephalexin antibiotics for fish. Fish Flex pet meds are effective against gram positive and some gram negative bacteria and are used to control common bacterial fish diseases like aeromonas and gill diseases. Fish Flex capsules contain 250 mg of cephalexin, and Fish Flex Forte contains 500 mg cephalexin capsules.

Fish Flex is a broad-spectrum antibiotic intended to treat a variety of bacterial infections in fish and other animals. The product is effective against both gram-positive and gram-negative bacteria.

Benefits of Fish Flex:

  • Effective against gram-positive and gram-negative bacteria
  • Can be used in fish, cats, and dogs
  • Treats a variety of infections, including urinary tract, skin, wound, and respiratory
  • Available in two strengths for easy dosing
  • Well tolerated

Use Fish Flex only as directed. Do not allow children to handle Fish Flex.

Directions for Fish:

  1. Add one Fish Flex 250 mg capsule to your aquarium for each 10 gallons of water. Alternatively, add one Fish Flex 500 mg capsule to your aquarium for each 20 gallons of water.
  2. Do a partial water change between 12 and 24 hours after treatment.
  3. Treat your aquarium again with the same dose 24 hours after the first treatment.
  4. Continue treating once daily for a minimum of 5 days and a maximum of 10 days. If no improvement is seen after 5 days of treatment, stop using Fish Flex and consult your veterinarian.

Directions for Cats and Dogs:

  1. Consult your veterinarian before using Fish Flex to treat dogs, cats, or other animals.
  2. Give dogs and cats 5 to 14 mg/lb every 6 to 8 hours by mouth.
  3. Offer with food to reduce possible side effects.
  4. Continue treatment until your veterinarian instructs you to stop.

Frequency of Use:

Use for as long as directed by your veterinarian. Premature discontinuation of Fish Flex, even if symptoms have cleared, may result in a return and/or worsening of the infection.


Store Fish Flex at room temperature in a tightly sealed container. Keep out of reach of pets and children.

It is a violation of Federal Law to use this product in a manner inconsistent with its labeling.

The active ingredient in Fish Flex, cephalexin, inhibits the synthesis of the cell wall in bacteria, resulting in their death. Cephalexin, a cephalosporin antibiotic, works against both gram-negative and gram-positive bacteria. With repeated use, some gram-negative rods, such as E. coli, may develop resistance to Fish Flex.

Fish Flex (cephalexin)

Fish Flex contains cephalexin, a cephalosporin antibiotic.


Keep this product out of reach of children and animals. Do not use or store in or near open flame or heat.

Fish Flex is intended for use in ornamental and aquarium fish only. It may also be used in cats and dogs. Do not give Fish Flex to humans.

CAUTION: Animals with a known or suspected sensitivity to cephalosporins should not use Fish Flex.

Although Fish Flex is usually well tolerated, it may cause severe diarrhea or other side effects in animals. Some cats and dogs may experience vomiting, loss of appetite, drooling, rapid breathing, or fever. Consult your veterinarian for advice.

Consult your veterinarian before using Fish Flex if your animal is currently taking anticoagulants, aminoglycosides, or any other medications or supplements. Interactions are possible.

Do not use Fish Flex in pregnant or lactating animals.