I know I saw somewhere here before that it's not possible to complete if we haven't already before the recent update because of the sea critters, but i was wondering if the other categories were completable or not? Like specifically, the giant mudskipper and sea cucumber. On the wiki it says they're found at Ocean (forest) or the Rice Field/ Estuary, and I have no idea where those are. Even if I can't truly complete the altar, it's all I really have left to do in the game right now
#Second Altar- completability?
dire lark
golden jackal
You can indeed catch those fish! Ocean forest is the river looking area that’s directly at the left exit of the farm
Rice field is below Kira’s house/left of jacks barn animals - use the stairs to get to the viewing platform & use rod at the ‘3’ level to land in the rice field waters
Estuary - below farm & above lookout - the bottom exit of your farm go left to the sacred tree, fish in any of the surrounding waters 
dire lark
Ah! Thank you!!! 😊😊