First off, I'm very ignorant and trying to learn. I've had a small cory in with a Beta in a one gallon tank for about 2 years. 2 weeks ago, the cory started swimming erratically, not being able to keep upright. If he settles on the bottom upside down, that's how he stays. (he looks dead, but if you tap on the tank, he moves immediately, sometimes turning himself upright in the process). However he lands is how he stays - even if its almost vertical. Sometimes the swimming looks normal for a second or two, then gets very wobbly and erratic again. I changed out the tank, but that didn't seem to help any. Any ideas on what's wrong and what I can do?
First hello and welcome to TFK :-D More information is needed to help to figure out what might be going on with your cory. Please provide the following information
1. Size of tank?
2. Water parameters
a. Ammonia?
b. Nitrite?
c. Nitrate?
d. pH, KH and GH?
e. Test kit?
3. Temperature?
4. FW (fresh water) or BW (brackish)?
5. How long the aquarium has been set up?
6. What fish do you have? How many are in your tank? How big are they? How long have you had them?
7. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)?
8. a. Any live plants? Fake plants?
b. Sand, gravel, barebottom?
c. Rocks, woods, fancy decors? Any hollow decors?
9. a. Filtration?
b. Heater?
10. a. Lighting schedule? What lights are used?
b. Any sunlight exposure? How long?
11. a. Water change schedule?
b. Volume of water changed?
c. Well water, tap water, RO water?
d. Water conditioner used?
e. Frequency of gravel/sand (if any) vacuumed?
12. Foods?
How often are they fed?
13. a. Any abnormal signs/symptoms?
b. Appearance of poop?
c. Appearance of gills?
14. a. Have you treated your fish ahead of diagnosis?
b. What meds were used?
15. Insert photos of fish in question and full tank shot if necessary
Sounds like it could possibly be a swim bladder issue, but the following info is needed to try to figure out what may be going on. Also corys are a very social fish and need to be kept in groups of about 5-6, but depending on the size of your tank and the type of cory you have will determine if you have the available room. Also what type of cory do you have?