[white spot above eye on Red Eyed Tetra]

If you can take Some pictures of sick fish

[Persistent Fin Rot]

I would use maracyn  because it been going for a prolonged period of time with the aquarium salt 1 table spoon for 2 gallons

[Fish Compatibility Advice in a Community Tank]

 I think most of them will eat guppy but if you have a lot of plant cover for fry to hide you should be ok

[Black water tank]

Great Looking tank

[koi with red lesions, disease ID?]

I looks like a bacterial infection  I would treat with aquarium salt 1 table for two  gallons for 5days if no lmprovement try maracyn or maracyn2

[What could be wrong with this guppy?]

No when treating with med you should always have extra aeration meds can drop oxygen levels stressing your fish more

[Betta Eye Damage]

I would start doing some 50%water changes to dilute the ammonia and treat with aquarium salt 1 table spoon for 2 gallons

[Best Canister Filters]

Fluval 07 series I have two at moment work great easy to clean  

[What could be wrong with this guppy?]

Hopefully it treatment works

[Cloudy water]

It could be free floating algae bloom I have problems for  month just put fluval  UV cleariser  hopefully work

[Hello from Los Angeles~ It's great to be a part of a forum again!]

Great tanks

[Helanthium tenellum question]

Nice tank

[Large black area on guppy's abdomen, varying degrees of swelling]

 If you have done med trio I would try aquarium salt 1 table spoon for 2 gallons for 1week

[How to Naturally increase KH and GH, Keep it stable - Recommendations for Guppy]

I use crushed oyster shells

[Fish identification thread!]

I have just looked in my book the spotted one looks like metynnis maculatus  max size 6-7in the gourami's a moonlight gourami's trichopodus microlepis 

[What could be wrong with this guppy?]

The guppy in bottom pictures look like they have a lighter patch on back with reddening of some scales you could have columnaris with secondary fungal infection that would explain the high mortality you have been seeing columnaris is a gram negative bacterial infection kanaplex or maracyn2  treat gram negative bacterial infection

3 hours ago, Schalk said:

Treated again this morning with Kanaplex. Had fish dying again after adding it. Dont understand this. Thought its medicine to cure. More fosh getting strange simptoms as in picture. Some white stuff on body and fin.

 

[Identify this snail]

Its Malaysia trumpet snails and I see one or two ramhorns 

[Habrosus Cory spinning like a torpedo/corkscrew]

Goldfish tetras and bristlesnose  

[Progress on my 20 Gallon Betta Aquarium]

Nice tank

[Fish identification thread!]

It  a golden tetra hemigrammus rodwayi

[Habrosus Cory spinning like a torpedo/corkscrew]

It could be swim bladder infection but the spinning could be a parasitic infection treat with aquarium salt 1 table spoon for 3  gallons and API general cure to cover all bases

[Please help....juvenile molly with prolapse]

Good to hear  

[Fish identification thread!]

Their differently a  species of metynnis it difficult tell what species it is 

[Tank background?]

I have a juwel aquarium 3D back ground  it looks like rocks

[Have farm raised Tiger Barbs turned into terror fish?]

Tiger barb only get aggressive when keeped in small groups the bigger group will stop them picking on one individual and spread aggression among the group