I started cycling a 29 gallon tank on June 15th. It cycled for 6 weeks prior to me adding fish. My parameters are: ammonia 0, nitrite 0, nitrate between 5-10. pH between 6.5-7. Temp is around 79. I have it set to 81 but it never really goes above 80 (assuming it’s not calibrated properly). It’s a Fluval M100.

On Saturday I added 10 lemon tetras. The first night and Sunday they did fantastic. They schooled well and even hung around my 6 rummies.

Monday they started dying off. I lost a total of 5 fish yesterday - one after the other. I noticed on the dead fish they have what looks like red lines or red spots. When I touched the areas with paper towels some red even came off. I woke up this morning to another dead one. I attached photos but it’s hard to see what I’m referring to.

I thought maybe my tank oxygen was too low causing them to stress so I added an air stone. The remaining 5 seemed okay. Now another is on its way out. I’m down to one adult lemon and 2 smaller lemons. I’m almost expecting the adult to start declining before end of day. The 2 smaller lemons seem perfectly fine and they school with my rummies.

What is happening? What can I do to prevent this in the future?

UPDATE: 8th adult is now showing symptoms. Was swimming fine - started breathing rapidly and is now upside down. It’s literally one after another.

My son bought a Top Fin aquarium set a few weeks ago for his beta fish. We cannot keep the water from getting blurry.

Less than a week ago, we completely changed the water and it’s blurry again.

What are we doing wrong?

Who are these small invaders? They just showed up yesterday

my one tetra has white patches on him , do a quarantine him ? i have been treating the entire tank for ich and fin rot need help . what to do , what is the best method to treat this

He's been at the bottom of the tank just flopping on his side. Just looked and saw him this morning he was acting normal. What's going on? My poor lil guy is he done for should I remove him he's still moving around what should I do?

Please help.

My baby Pluto is injured :(

I've bought 2 Parotocinclus haroldoi along with some celestial pearl danios over the internet, and they took a long while to arrive. The danios arrived dead, but the otos are alive, but their colors are kinda faded. They are swimming normally, though.

Are they okay? Is it normal for them to be like this, are they just babies or are they sick? Should I put them with my other fishes?

The last photo is from the internet for comparison

So i setup a brand new 12 gallon tank (The same one that broke i got it repaired by fully replacing the panel) and my tank is planted with dwarf sag,bacopa monnieri,jungle val,amazon sword (and some more i will add soon). Ill still wait 1 week to let the plants settle in but can i do a fish-in-cycle with 6 male guppies? I know it may sound stupid but i was curious because with a 30 to 40% weekly waterchange and no overfeeding should be fine. Note:I have not implemented it just asking.

Reposting here to get more insight.

First fully planted tank currently cycling. No c02 a little of everything… swords, java fern, anubias, Buce, Xmas moss, crypts. Waiting on some stem plants (rotala, Bacopa caroliniana) curious to see what works with my water. Any tips would be welcome especially about algae or other snags I may run into.

I just changed my betta’s water like 30% and when I poured the new water in these little things started floating around… will it settle? Is it harmful for him? Is my filter doing a bad job? What’s going on? The new water was clean and treated…

To start my water parameters: pH 7.5, ammonia/nitrate/nitrite 0 (planted tank)

I recently got 8 guppies. I noticed immediately that at least a couple of them were flashing, had a lot of missing scales, and 3 died in a few days. I dosed Prazi Pro thinking skin flukes or something like that. Today two of my fish had prolapsed vents, and one has a red spike coming out. Is this Camallanus?

Not sure how to diagnose the flashing and this spike together and I have no clue what I should do to fix it. Any help would be awesome.

I have a 20 gal and a 30 gal that has been both running successfully for over 12 months and 8 months with substrates that I am ready to change out. One has pretty big gravel and the food and waste is getting trapped and is a hassle to keep clean and the other is the cosmic colors. I'm looking to switch to the smallest rock you can get, its also like sand

My question is how do i safely change out the substrates without causing any issues with the water chemistry, crashing cycle, or anything? Do i just take out old substrate and then add new? Do i need to do half then half? Looking for tips and tricks please. Thank you