White spot during tank cycling — what to do

White spot appearing mid-cycle is one of the worst timing combinations in fishkeeping — you've got vulnerable fish, an unstable tank, and most standard ich treatments will kill off the beneficial bacteria you're trying to establish. The good news is there are ways through this without starting over. Before I point you in the right direction: how far into the cycle are you, roughly — are you seeing ammonia and nitrite spikes, or has the tank started to settle? And how many fish are affected?

Okay, that's really helpful. Three weeks in with nitrite still spiking means your tank is at the most stressful point of the cycle for fish — high nitrite suppresses their immune system, which is almost certainly why the ich has taken hold. The critical thing here is that you can't just wait it out. Ich is a parasite with a lifecycle, and the free-swimming stage is the only one treatments can kill. If you do nothing, it will spread to all six fish fast. The other complication is that most liquid ich treatments contain chemicals — malachite green, formalin — that are hard on biological filtration. What you want is a salt-based treatment, which is far gentler on your cycling bacteria.

Salt does work for ich, and you're right to flag tetras — they're softer-water fish and high salt concentrations stress them. The key is using a measured, low-dose aquarium salt specifically formulated for this, not table salt and not the concentrations used for goldfish. The product I'd point you to is NT Labs Anti-Parasite Salts. It's dosed precisely for tropical fish, it's been formulated with the bacterial cycle in mind, and the treatment regime is clear and straightforward. Use it alongside daily 25% water changes — that's essential right now anyway to keep nitrite down, and it also physically removes ich from the water column. The water changes are doing double duty.

Yes, raising the temperature to around 28°C speeds up the ich lifecycle, which means the parasites hit the treatable free-swimming stage faster and your treatment window shortens overall. For neon tetras, 28°C is at the top of their comfortable range but manageable for a short treatment period — don't go higher. Do it gradually, about 1°C per hour, and make sure your tank is well aerated because warmer water holds less oxygen. Combine the NT Labs salt treatment with the temperature raise and daily water changes, and you've got a genuinely effective protocol. Keep testing your water through this — if nitrite spikes badly, do an extra water change rather than skipping one.

At 28°C with salt treatment, you're typically looking at 10 to 14 days for a full course. The spots may actually look worse in the first few days — that's normal, it's the ich completing its cycle before the free-swimming stage gets hit. You'll know it's working when no new spots appear and existing ones drop off. Keep treating for the full duration even if fish look clear early — ich has a stubborn lifecycle and stopping too soon is how it comes back. Once treatment is complete, do a larger water change to remove the salt gradually, and your cycle should still be ticking along in the background.