Description
Fish Cin (Fix Cin) gives aquarium keepers clindamycin in a 100-count bottle of 150 mg capsules, made by Aqua Soma Labs for freshwater and saltwater fish. The label dose is one capsule per 10 gallons, repeated daily for 5 to 10 days.
- Active ingredient
- Clindamycin
- Strength
- 150 mg per capsule
- Bottle size
- 100 capsules
- Label dose
- 1 capsule per 10 gal (38 L)
- Course
- Once a day for 5 to 10 days
- Made by
- Aqua Soma Labs, USA
What fish clindamycin is good at, and what it isn't
Clindamycin is a lincosamide. It works on gram-positive bacteria and on anaerobes, the bacteria that thrive without oxygen deep in damaged tissue. That makes it a specialist rather than a general-purpose antibacterial. Aquarists use Fish Cin for:
- Deep puncture wounds and bites that swell instead of healing
- Abscesses: raised, pus-filled lumps under the skin
- Ulcers that stay open for weeks while the water is clean
- Jaw and mouth injuries that become infected after a fight or a net
Clindamycin is weak against gram-negative bacteria. That rules it out as a first choice for columnaris (the cotton-like mouth and saddle patches), for fast-spreading red ulcers, and for dropsy. For those, choose Fish Flox, Fish Doxy, or Fish Zithro.
Fish Cin dosage by tank size
| Tank | Liters | 150 mg capsules per day |
|---|---|---|
| 10 gal | 38 L | 1 |
| 20 gal | 76 L | 2 |
| 30 gal | 114 L | 3 |
| 40 gal | 151 L | 4 |
| 55 gal | 208 L | 5½ |
| 75 gal | 284 L | 7½ |
Fix Cin comes in one strength, 150 mg. If you've seen 300 mg fish clindamycin elsewhere, the math is simple: two 150 mg capsules equal one 300 mg dose, and the amount per gallon on your label is what counts. Follow your bottle's label over this chart.
Treating with Fish Cin
- Hospital tank first. Wounded fish heal faster without tank mates nipping at them, and the dose stays accurate.
- Remove absorbers. Take out carbon and resins, switch off UV, and keep aeration strong.
- Mix the dose. Empty the capsules into a cup of tank water, stir until dissolved, and add it slowly.
- Every 24 hours. Change part of the water, then dose again for the full volume.
- Look at the wound edges. By day 5 swelling should go down and the edges should look pinker and cleaner. No change means the bacteria are probably gram-negative; stop and switch approach.
- Finish. Complete the course while the wound closes, then do a large water change and put carbon back.
How long a 100-capsule bottle lasts
One bottle is five full 10-day courses in a 20 gallon hospital tank, or two and a half in a 40 gallon tank. At list price each capsule costs about $0.60, so a 10-day course in 20 gallons comes to about $12.00. If you quarantine fish often or keep several tanks, that's one of the lowest costs per course in the line.
Fish Cin compared with its neighbours
| Product | Covers | Choose it for |
|---|---|---|
| Fish Cin | Gram-positive and anaerobes | Deep wounds, abscesses, stubborn ulcers in clean water |
| Fish Flex | Gram-positive, some gram-negative | Surface ulcers and wounds |
| Fish Pen | Gram-positive | Early, mild wound infections |
| Fish Flox | Gram-negative | Columnaris-type and aggressive ulcers |
Our fish antibacterials overview puts all nine side by side.
Handling and tank notes
- Test ammonia and nitrite every day; clindamycin can slow the biofilter.
- Keep invertebrates and corals out of the treated water.
- Wounds close faster in stable, warm-enough water with low nitrate. Fix the water as you treat.
- Don't combine Fish Cin with other antibacterials unless an aquatic veterinarian recommends it.
- Wash your hands after handling capsules. Store the bottle closed and dry, out of reach of children and pets, and don't flush unused capsules.
Fish Cin questions
Fish Cin and Fix Cin: one product or two?
Fish Cin is the name aquarists search for clindamycin capsules for fish. Fix Cin is Aqua Soma Labs' 150 mg clindamycin capsule, so this page carries both names.
Does Fish Cin treat columnaris?
It isn't a good fit. Columnaris bacteria are gram-negative, and clindamycin is weak against them. Fish Flox, Fish Doxy, or Fish Zithro are better choices.
Can I use it in a saltwater aquarium?
Yes, the label covers freshwater and saltwater ornamental fish. Treat marine fish away from corals and invertebrates.
Why only a 100-count bottle?
At one 150 mg capsule per 10 gallons, a single course in a mid-size tank uses 20 to 40 capsules. The 100-count bottle covers several courses without reordering.
Where can I buy fish clindamycin?
It's one of the harder fish antibacterials to find locally. We keep Fix Cin 150 mg in stock and ship from Missouri the same or next business day.
For aquarium and ornamental fish only.
