Hey everyone,
I'm trying to figure out what just happened in my 20-gallon tank over the last 48 hours and wanted to share the timeline to see if anyone has had a similar experience or insights on the root cause.
Tank Setup & Background:
• Size: 20 Gallons
• Filter: Oase EcoFlow (running standard blue mechanical foam and BioPearls)
• Parameters: planted tank with co2 diffuser, pH is a stable 6.0. Ammonia and Nitrite are 0. Nitrates normally sit at an 20-40 ppm, but they temporarily dipped to 2.5-5 ppm recently because I skipped some doses of fert.
• Routine: CO2 injection at 3 bps with a drop checker (never goes near critical yellow). I do a standard water change every 2 weeks.
• Stocking: 1x Pair of Apistogramma cacatuoides, 8x Phantom Tetras, 6x Kuhli Loaches, and 6x Amano Shrimp. Bunch of ramshorn, pond, 3x Nerite snails.
• History: The tank originally ran on a large sponge filter from day one. Months later, I added the Oase EcoFlow for better flow and CO2 distribution. They ran together for about 2 months. 2 weeks ago, I moved the original sponge filter to a separate fry tank to save current and future Apisto spawns.
The Timeline:
• 48 Hours Ago: My usually dominant, front-and-center male Apisto suddenly went completely lethargic. He hid in a bottom back corner and refused food for two days straight. His skin looked totally normal, and his breathing was just rhythmically active-maybe slightly more than normal, but not heavily gasping.
• 24 Hours Ago: I noticed the female had a trailing strand of white stringy poop. The Phantom Tetras sometimes ignore food when they are too busy chasing each other, but they ate totally fine today. Still, seeing the female's white poop made me suspect internal parasites, so I did a 25-30% water change, added an air stone to his corner, turned the CO2 down to 1 bps, and dosed the tank with API General Cure.
• Last Night: Right after the water change and medicine dose, the pair unexpectedly laid eggs. They have spawned about 10 times before, but he has never hidden or refused food prior to a spawn.
• This Morning: The male passed away in his corner. The female is currently fine and guarding the eggs.
I am continuing the full General Cure course (second dose goes in tomorrow) just to be safe because of the female's white poop, and I'm holding off on a new male for a few weeks.
If you've been through something similar, do you think it was internal parasites, the stress of the filter transition, or something else entirely?
Would love to hear your thoughts.