Video below shows my 8-9 inch black ghost knife swimming vertically. It is so odd behavior that I thought I would see what everybody else thinks. It's also weird for him because he never comes out when lights are on. He started swimming this way last night, is there something wrong? Is he getting more comfortable with the tank and this is normal? We've had the tank running since the end of February, cycled it with established media, and the ghost has been in it since. Tank is 300 gallon with 55 sump and fx6, water parameters this morning were: ph: 7.4-7.6, ammonia: 0, nitrite: 0, and nitrate: 40. Testing with API master test kit. Any insight to his behavior is appreciated!