My guppy died please help I can't work out why?

[Tim Monteverde]

I have a 30L fish tank with an external filter, 150L/H. I had 3 guppies, two female and one male, I've had them for around two weeks. Before I got my fish I did a fishless cycle for four weeks, I then added my guppies, I have done 20% water changes every 2 days and not missed one yet, I use seachem prime every time I do a water change to help with amonia and dechlornate my tap water. The tap water is quite hard and sends my test strips almost as dark as they go, pH is 7. Since getting the fish I added two red cherry shrimp, and an assasin snail to help keep the maylasian trumpet snails which came in on some plants I got right at the start under control which he seems to be doing a great job of.

This morning when I came to the tank, after doing my usual water change last night, my poor male guppy was dead on the bottom of the tank, I got him out with my net and then began trying to work out how he died, both females appear completely normal, I should mention they're both pregnant with large gravid spots on them, the shrimps are completely fine and so is my assasin snail. I tested my water nitrite and nitrate were both almost exacly 0. I don't have an amonia test kit but there's one on the way now, but I'd be supprised if the problem was ammonia as I treat with seachem prime and I do so many water changes.

Also it might be important to know I add 2ml of tnc fertiliser every week for my plants and 0.5ml of tnc carbon every day (both recommended dosage for my tank size)

Does anybody have any idea my my fish might have died I know my tank is quite heavily stocked but I presumed with a lot of maintaince I could keep it stable


Thanks Tim

 

[Colin_T]

What did the fish look like when it died?

What is in the TNC fertiliser and carbon?
If you are adding carbon to the tank there is no need to due to the amount of carbon dioxide (CO2) in the atmosphere and in the water. CO2 is produced by bacteria in the filter, substrate, fish and the plants also produce it at night when it's dark.

Iron based plant fertilisers are the best aquatic plant fertiliser. Most of the major nutrients required by plants are obtained from fish food and waste in the water.

If you are doing water changes every couple of days, you will be diluting the plant fertiliser when you do the water change. You should be fine doing a 75% water change once a week and adding the fertiliser after the water change.

 

[Tim Monteverde]

Here's the label for the tnc fertiliser, the only reason I use it is just as a small boost for the plants that are in there, I'm not too concerned about them I am primarily focused that everything in the tank is alive and good hence the reason I do the small changes more frequently. Because I heard the shrimps can be quite sensitive to large water changes.