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White crusty mouth on Betta


Registered Member
My betta suddenly has a white crusty mouth today. He's listless, barely breathing. He appeared fine last night.

1. Size of tank? 55 gallon

2. Water parameters Don't know, just ordered test kit yesterday
a. Ammonia?
b. Nitrite?
c. Nitrate?
d. pH, KH and GH?
e. Test kit?

3. Temperature? 78F

4. FW (fresh water) or BW (brackish)? FW

5. How long the aquarium has been set up? about 6 weeks

6. What fish do you have? How many are in your tank? How big are they? How long have you had them? 5 Dwarf Gouramis, 6 mollies, about 20 nebula steel guppies (includes fry), red tail shark, bristlenose pleco, algae eater. 5 cherry veiltail barbs, 1 betta. Shark, pleco and algae eater came with the tank and are 2 years old so about 5-6" each. The rest of the fish have been added sporadically since it was set up. Recently had 5 guppies, 1 molly and 4 gouramis added Dec. 29. Lost one gourami and all 5 guppies. One guppy was bloated, other 4 were thin and looked like their tail fins were tore up. Added the Nebula Steel and fry on Jan 1st and all appear normal. Betta has been in the tank within a week of setting it up and has been fine until this morning.

7. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)? No quarantine tank availalbe

8. a. Any live plants? Fake plants? Fake plants
b. Sand, gravel, barebottom? gravel
c. Rocks, woods, fancy decors? Any hollow decors? some decorations and bubblers

9. a. Filtration? Marineland Penguin 350
b. Heater? Aqueon 200 watt

10. a. Lighting schedule? What lights are used? about 7 a.m. to 11 p.m. Aqueon Reflector?
b. Any sunlight exposure? How long? None

11. a. Water change schedule? Last done 12/24 and again yesterday
b. Volume of water changed? about 25-30%
c. Well water, tap water, RO water? Tap
d. Water conditioner used? NovAqua Plus
e. Frequency of gravel/sand (if any) vacuumed? every water change

12. Foods? Tetramin
How often are they fed? once a day

13. a. Any abnormal signs/symptoms? White crusty mouth, listless. Placed him in a bag in the tank because the one gourami is trying to pick on him now that he's sick.
b. Appearance of poop? ??
c. Appearance of gills? Fine I think

14. a. Have you treated your fish ahead of diagnosis?
b. What meds were used?
Had a bottle of Nutrafin Cycle that I put in last night thinking it would help the system while I waited on my water test kit to arrive.

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No freelancing!
Make sure the top of the bag is open--bettas need access to surface oxygen.

When you say fish 'came with the tank', does that mean you purchased a full setup, moved it, and start adding fish? So the filtration has been running longer than you have owned the tank?

Just guessing, but I think the ammonia/nitrogen is going to be high. When the tank was moved, a few bacteria colonies were lost, then adding a bunch of fish overwhelmed it. High ammonia levels are bad for fish. The 'original' fish were likely not getting the best care--common when someone is looking to get rid of a setup--so are a bit more resilient to poor conditions than the additions.

Stop adding fish until you can get a test kit and verify the tank is cycled. Once that's done, start researching fish before adding them--gourmies and bettas, and guppies are not a good combination. Adding 20 fish at once is a sure-fire way to breaking a cycle--that many fish at once adds more ammonia faster than the bacteria can reproduce.

The betta probably has a bacterial infection from being in poor water conditions, and being picked on.

In terms of food--Tetramin makes different products, bit if you are only feeding one type, it's going to cause a problem. The algae eater and bristelnose (and shark and mollies) will all appreciate some greens--either fresh veggies, or algae wafers.


Global Moderator
Staff member
krob- Welcome!

That's a nice looking setup you have.

Like OrionGirl suggested, don't add anything further to the tank until you can test your water parameters. That's a LOT going on in this 55. A lot of fish.

In the meantime, I get a good dechlorinator that can detoxify ammonia. There's lots of'em available. One of the most popular is Seachem Prime, or Safe (granular form). Do at least 50% water changes often. I'd probably do one 50% WC per day until I got this sorted.


Registered Member
The tank had been set up for about 2 years and came with 9 original fish. I only kept 3 of those which consisted of the Red Tail Shark, Bristlenose Pleco, and Algae Eater. We moved the tank 11/21/2017 and had to completely empty it to do so. I set it up with the original 9 fish and left it for about 7-10 days before adding anything to it.

Finally got my test kit today. Parameters are the following:
pH: 7.8 Planning to order API Proper pH 7.0
Ammonia: 0
Nitrite: 0
Nitrate: 40 Should I get API Nitra-zorb or Seachem Matrix?

The betta died almost as soon as I had my original post up but he was not getting picked on at all. Even my red tail shark is very mild and none of my fish have been overly territorial or picking on one another. My red tail shark was lethargic and getting the "cotton mouth" thing about that same time. I also saw a couple guppies with it and they died within 24 hours. I shut my heater down and the water went down to 75 but hasn't gone below that. I ordered Kanaplex and Fluran 2 which has yet to arrive. In the mean time was able to get ahold of API Triple Sulfa and started that treatment along with adding 1 TBSP of salt per gallon to the tank per the recommendations of the article at americanaquariumproducts. The shark looks like the cotton mouth is receding and has been a little more active. I haven't lost any fish today. Fingers crossed. Today will be a 25% water change and the 3rd treatment of Triple Sulfa. I'm going to finish the 4th treatment tomorrow, then do the 25% water change the following day. The Kanaplex and Furan 2 should be here by then. Should I still do that treatment as well?


Global Moderator
Staff member
I would personally avoid any additives to modify your pH and the easiest and probably most reliable way to lower nitrates is to change water. Most of us do weekly water changes to keep our nitrates so they don't exceed 20ppm.

I have no experience with the meds you're adding to the water and again, would totally avoid doing so unless you know exactly what you're treating for and how it will effect the rest of the stock in your tank and your beneficial bacteria.

Stores will recommend meds because they need to sell stuff. Simple as that.