75 Gallon Established Tank - Challenges with Dying Fish

[GailLaForest]

Good Morning,

I'm challenged with an ongoing problem in my 75 gallon tank that I can't seem to get ahead of.  I'm going to supply lots of detail, please read through before replying. Thanks!

Water Parameters:

• pH                          7.2-7.6
• Nitrates                  10
• Hardness                75
• Nitrite                     0
• Ammonia                0
• KH/Buffer                180
• Water Temperature 76º-78º
• Chlorine                   0

There are currently 2 Cories, 2 Dwarf Albino Cories, 1 Pearl Gourami, 3 Otocinclus, 3 Kuhli Loaches, 1 Siamese Algae eater, 1 American Flag Fish, 1 Dwarf Rainbow Fish, 6 Green Neon Tetras, 6 Cherry Barbs, 3 Ember Tetras, 1 Nerite Snail, and 3 Mystery Snails plus several small volunteer snails from plant purchases.  A total of 29 fish and 4 snails.  They are fed frozen brine shrimp, frozen tubifex worms, Bug Bite flakes, and algae tabs.  I do not over-feed.  I do a partial water change every 2 weeks.

The tank is planted with Anubias Barteri, Tiger Lotus, Red Flame Sword, Vallisneria, and Water Wisteria. I feed plants once a month. It also has a variety of rock and driftwood, all thoroughly cleaned and treated before being placed in the tank.

The tank has been set up with fish since August 2023, it was first filled with substrate, hardscape, and water in May and allowed to cycle through the summer.  After fish were introduced I had algae bloom and it took a little while to dial in light levels and duration, no problems with this now.  I have 2 large sponge filters and a 300 watt aquarium heater.

To date I have lost 6 Cardinal Tetras, 5 Dwarf Rainbows, 2 Pearl Gourami, 2 Cherry Barbs, and 4 Nerite Snails.  Fish numbers have been consistent, I have replaced fish only as I've lost them.  The first deaths were the Cardinal Tetras in October.

Symptoms are, in the order that I see them - lethargy, labored breathing, protruding eyes, the fish stops eating and then dies.

I have treated the entire tank with Expel-P, I have isolated sick fish in a 10 gallon heated aquarium and treated with aquarium salt (https://www.aquariumcoop.com/pages/help-center#/collection/5075/article/25225), and, at another time, with a combination of Expel-P and Maracyn.  The last fish I quarantined and treated was a female pearl gourami, she seemed to recover, she was active and eating.  I moved her back into the big tank after 10 days where she died within 3 days without showing any apparent symptoms.  The attached photo shows her 2 days after being reintroduced.

I have no idea what is going on, am I doomed to slowly watch my fish die off?  I would be most appreciative of any and all suggests as to what I might do to stop this from happening.

In Peace,
Gail

[Colu]

First thing I would do is add no new fish till you have determined the cause of the death and effectively dealt with problem couple of questions did the fish start to show theses symptoms just after a water do you use a water dechlorinator like prime when doing water changes have you notice any sunken belly white stringy poop how many course of expel p have you done on the main tank @GailLaForest

[GailLaForest]

Good Morning,

Good points, I haven't added any new fish in at least two months and have lost the snails, and 2 gouramis since then.

The water here is from a community well, chlorine is never added to it and water tests right out of the tap are the same as I quoted above with the exception of slightly higher nitrates, my thinking is that is because of the plant food added to the tank. I usually do not condition the water.

I will watch for sunken belly specifically. The fish stop eating and just get really thin overall. I did notice a worm emerging from one of the dead fish and treated the entire tank with Expel-P exactly as they say to use it. The entire tank has had only that one full course. I have also used Expel-P in the quarantine tank this last time for the sick gourami even though she didn't show any signs of parasitism.

Thanks for the reply.

 

I would add that overall the tank is in excellent shape. The fish that are in pairs are regularly spawning, including the cories which surprised the heck out of me!

[Colu]

On 4/13/2024 at 7:05 PM, GailLaForest said:

Good Morning,

Good points, I haven't added any new fish in at least two months and have lost the snails, and 2 gouramis since then.

The water here is from a community well, chlorine is never added to it and water tests right out of the tap are the same as I quoted above with the exception of slightly higher nitrates, my thinking is that is because of the plant food added to the tank. I usually do not condition the water.

I will watch for sunken belly specifically. The fish stop eating and just get really thin overall. I did notice a worm emerging from one of the dead fish and treated the entire tank with Expel-P exactly as they say to use it. The entire tank has had only that one full course. I have also used Expel-P in the quarantine tank this last time for the sick gourami even though she didn't show any signs of parasitism.

Thanks for the reply.

 

I would add that overall the tank is in excellent shape. The fish that are in pairs are regularly spawning, including the cories which surprised the heck out of me!

With what you described I would treat all the fish with expel p it can take four course of treatment one week apart active ingredient in expel p levamisole can be harmful to snails so I would remove them before treating so you would treat week 1 week 2 week 3 week 4